After having been working with images and after closing, the name of some of them (I didn't found the rule describing which one would be kept) remain listed in the Window tab.
Apparently these images are still occupying RAM.
I didn't found another solution but restarting Fiji between each analysis.

Information about your version of Java:

  os.arch => x86_64
  os.name => Mac OS X
  os.version => 10.9.3
  java.version => 1.6.0_65
  java.vendor => Apple Inc.
  java.runtime.name => Java(TM) SE Runtime Environment
  java.runtime.version => 1.6.0_65-b14-462-11M4609
  java.vm.name => Java HotSpot(TM) 64-Bit Server VM
  java.vm.version => 20.65-b04-462
  java.vm.vendor => Apple Inc.
  java.vm.info => mixed mode
  java.awt.graphicsenv => apple.awt.CGraphicsEnvironment
  java.specification.name => Java Platform API Specification
  java.specification.version => 1.6
  sun.cpu.endian => little
  sun.desktop => null
  file.separator => /

The up-to-date check says: REMIND_LATER

Information relevant to JAVA_HOME related problems:

  JAVA_HOME is set to: null
  imagej.dir => /Applications/Fiji_Bug.app

Information about the version of each plugin:

Activated update sites:
ImageJ: http://update.imagej.net/ (last check:20140711230647)
Fiji: http://fiji.sc/update/ (last check:20140709213742)
BioVoxxel: http://sites.imagej.net/BioVoxxel/ (last check:20140711095200)
<ANONYMIZED>: <ANONYMIZED> (last check:20140603110822)

Files not up-to-date:
  38917f2e (MODIFIED) 20140630151408 Contents/Info.plist
  2724b6f5 (UPDATEABLE) 20140702183923 jars/imagej-2.0.0-rc-8.jar
  1d8f8610 (UPDATEABLE) 20140702183928 jars/imagej-legacy-0.5.19.jar
  7f4151c4 (UPDATEABLE) 20140709153856 jars/imagej-ui-swing-0.4.9.jar
  0f1fa7f7 (UPDATEABLE) 20140702183917 jars/rsyntaxtextarea-2.5.0.jar
  a7af3ea6 (UPDATEABLE) 20140702183921 jars/scijava-common-2.25.0.jar
  c9403b7f (LOCAL_ONLY) 20081204122732 luts/Ash.lut
  59f03146 (LOCAL_ONLY) 20050906160328 luts/Blue Pale.lut
  3e25836f (LOCAL_ONLY) 20041021171042 luts/Blue_Hot.lut
  a5152a57 (LOCAL_ONLY) 20010124121354 luts/Brown.lut
  94ab6188 (LOCAL_ONLY) 20040211135714 luts/Cornflower.lut
  d88bad71 (LOCAL_ONLY) 20040211151324 luts/Cyan Pale.lut
  3e2e5fd2 (LOCAL_ONLY) 20070419092312 luts/FLIM.lut
  fcf7f6c6 (LOCAL_ONLY) 20091127134508 luts/GB.lut
  ff917442 (LOCAL_ONLY) 20040304093246 luts/Green Fire blue2.lut
  9b3acd7d (LOCAL_ONLY) 20030317120436 luts/Green Fire.lut
  a6c0c8a2 (LOCAL_ONLY) 20010124120404 luts/Green Hot.lut
  2ef5d4c0 (LOCAL_ONLY) 20050906160430 luts/Green Pale.lut
  a6352819 (LOCAL_ONLY) 20081216155930 luts/ICA_black.lut
  989dff46 (LOCAL_ONLY) 20030703153058 luts/Lemon Hot.lut
  14799069 (LOCAL_ONLY) 20040211151126 luts/Magenta Pale.lut
  c3ded429 (LOCAL_ONLY) 20010124120034 luts/Orange.lut
  b000c4c5 (LOCAL_ONLY) 19991005125506 luts/Pink Hot.lut
  03835113 (LOCAL_ONLY) 20040223140804 luts/Purple.lut
  76e26325 (LOCAL_ONLY) 20031017132556 luts/Rainbow Smooth.lut
  da09a56e (LOCAL_ONLY) 20071107130530 luts/Rainbow_Bands.lut
  abc28f3a (LOCAL_ONLY) 20010726144126 luts/Ratio.lut
  1b67628e (LOCAL_ONLY) 20030328145516 luts/Red Fire.lut
  6706de8e (LOCAL_ONLY) 20050906160354 luts/Red Pale.lut
  a42db0ac (LOCAL_ONLY) 20081224090342 luts/Red-Cyan.lut
  17cb784c (LOCAL_ONLY) 20140113094750 luts/Red-Green.lut
  81619073 (LOCAL_ONLY) 20040211151010 luts/Yellow Pale.lut
  ac38884b (LOCAL_ONLY) 20060606101730 luts/ZProjection of PSF.lut
  d95f5994 (LOCAL_ONLY) 20081216160824 luts/orange_pink.lut
  7a1e4a15 (LOCAL_ONLY) 20081224090800 luts/temp.lut
  c219a947 (LOCAL_ONLY) 20140113101916 luts/yellow_black_magenta.lut
  df6ff5d8 (LOCAL_ONLY) 20140113104029 luts/yellow_green_black_blue_magenta.lut
  5d501548 (LOCAL_ONLY) 20041116151558 macros/360¯ 3D_project....txt
  eb36cbbb (LOCAL_ONLY) 20140612124357 macros/BG_subtration_from_ROI.txt
  9cf278cc (LOCAL_ONLY) 20131128144456 macros/Copie logo.ijm
  0c74ea4a (LOCAL_ONLY) 20140612150133 macros/Hyperstack_Z_color.ijm
  c40123b1 (LOCAL_ONLY) 20130212172949 macros/cruseur_ligne_blanche.ijm
  2b0f69b3 (LOCAL_ONLY) 20121230151234 macros/curseur_darkgreen.ijm
  9e69722c (LOCAL_ONLY) 20121230151151 macros/curseur_lightgreen.ijm
  d6fbc4a5 (LOCAL_ONLY) 20120731160635 macros/curseur_red.ijm
  cdf2ee26 (LOCAL_ONLY) 20121230150819 macros/curseur_yellow.ijm
  065c894b (LOCAL_ONLY) 20110203165604 macros/macro_vtk/openVTK.ijm.txt
  5f2bd998 (UPDATEABLE) 20140710155731 macros/toolsets/BioVoxxel_Toolbox.ijm
  293cf6de (LOCAL_ONLY) 20110324140250 macros/vtkProjector.ijm
  6dd8406a (LOCAL_ONLY) 20121106134510 macros/vtkProjector_2.0.ijm
  48b81454 (LOCAL_ONLY) 20121106161357 macros/vtkProjector_3.0.ijm
  a29c9929 (LOCAL_ONLY) 20120213090245 macros/vtkProjector_offset_adaptatif.ijm
  85648951 (LOCAL_ONLY) 20110506095754 macros/vtkProjector_show_progress.ijm
  dac42df8 (LOCAL_ONLY) 20110720085740 macros/vtkProjector_show_progress_offset_390.ijm
  6d5c5d7b (LOCAL_ONLY) 20110506095816 macros/vtkProjector_show_progress_one_channel_offset217.ijm
  c13d712f (LOCAL_ONLY) 20111104101318 macros/vtkProjector_show_progress_one_channel_offset390.ijm
  d7330568 (LOCAL_ONLY) 20111104145930 macros/vtkProjector_show_progress_one_channel_offset390_premier_tps_est_1.ijm
  6f85a280 (LOCAL_ONLY) 20110705100716 macros/vtkProjector_show_progress_one_channel_vtk_gz.ijm
  ab9d3759 (LOCAL_ONLY) 20110905145746 macros/vtkProjector_show_progress_one_channel_vtk_gz_sans_median.ijm
  73e6d01d (LOCAL_ONLY) 20110607144352 macros/vtkProjector_show_progress_type_proj.ijm
  ac03a943 (LOCAL_ONLY) 20110607134006 macros/vtkProjector_show_progress_type_proj_save_movie.ijm
  5fae3851 (LOCAL_ONLY) 20110607144842 macros/vtkProjector_show_progress_type_proj_save_movie_tz.ijm
  c434fcf2 (LOCAL_ONLY) 20110905141140 macros/vtkProjector_show_progress_vtkgz.ijm
  bdd52dda (LOCAL_ONLY) 20110905142036 macros/vtkProjector_show_progress_vtkgz_pas_de_median.ijm
  75cd6828 (LOCAL_ONLY) 20120919153920 macros/vtkReslicer_MAC.ijm
  1a2fcb3a (LOCAL_ONLY) 20140704102007 macros/vtkReslicer_MAC_GZ.ijm
  63cc0ea9 (LOCAL_ONLY) 20130703123439 macros/vtkReslicer_MAC_GZ_OF262.ijm
  04c96420 (LOCAL_ONLY) 20110803153700 macros/vtkReslicer_show_progress_one_channel_offset217.ijm
  08fe6d13 (LOCAL_ONLY) 20140627102432 macros/vtk_converter_16to8bits.ijm
  d2b71fae (LOCAL_ONLY) 20140704101132 macros/vtk_dimention.ijm
  3e5d8301 (LOCAL_ONLY) 20120913172435 macros/vtk_projector_MAC.ijm
  b9c74c4e (LOCAL_ONLY) 20120914133652 macros/vtk_projector_MAC_GZ.ijm
  f712a7a1 (LOCAL_ONLY) 20121018123502 macros/vtk_projector_MAC_GZ_OF262.ijm
  7a89c6cd (LOCAL_ONLY) 20140627131721 macros/vtk_slices_addition.ijm
  5d42a76c (LOCAL_ONLY) 20140620162054 macros/zproj_LIF_headless - copie.txt
  e213c1e3 (UPDATEABLE) 20140710155731 plugins/BioVoxxel/Speckle_Inspector.class
  d3e4a544 (LOCAL_ONLY) 20090213144024 plugins/CIPF/Chart_White_Balance.class
  b7b0131d (LOCAL_ONLY) 20090213144758 plugins/CIPF/Color_Classification$ColorClass.class
  0b47748c (LOCAL_ONLY) 20090213144758 plugins/CIPF/Color_Classification.class
  c2f9e5c4 (LOCAL_ONLY) 20090213125044 plugins/CIPF/Util.class
  5fdc21b9 (LOCAL_ONLY) 20061111000356 plugins/Changes.txt
  c968d55e (LOCAL_ONLY) 20110429092628 plugins/CircadianGeneExpression_.jar
  ff31d874 (LOCAL_ONLY) 20140113094418 plugins/ColorPanel.class
  8833c6df (LOCAL_ONLY) 20070330134350 plugins/Colour functions/Align_RGB_planes.class
  ed9a6168 (LOCAL_ONLY) 20070416131050 plugins/Colour functions/Colour_Balance.class
  0cb26198 (LOCAL_ONLY) 20080104080640 plugins/Colour functions/Colour_Composite_Merge.class
  05883551 (LOCAL_ONLY) 20050512154136 plugins/Colour functions/Colour_Correct.class
  6114c982 (LOCAL_ONLY) 20090622132532 plugins/Colour functions/Colour_ProfilePlot.class
  365af84e (LOCAL_ONLY) 20050201153722 plugins/Colour functions/Colour_merge.class
  e5491b0b (LOCAL_ONLY) 20071216145326 plugins/Colour functions/Composite_RGB_Merge.class
  38b7d101 (LOCAL_ONLY) 20070214142148 plugins/Colour functions/RGB_Gray_Merge.jar
  f242bdf4 (LOCAL_ONLY) 20090623071522 plugins/Colour functions/RGB_Line_Profile.txt
  b8a2b414 (LOCAL_ONLY) 20060801092546 plugins/Colour functions/RGB_Measure_Plus.class
  7cf305a0 (LOCAL_ONLY) 20040408161504 plugins/Colour functions/RGB_Profiler.class
  09874319 (LOCAL_ONLY) 20080623073956 plugins/Colour functions/RGB_to_Montage.class
  6ad1190e (LOCAL_ONLY) 20061011121404 plugins/Colour functions/Recolor_RGB_to_MGB.txt
  67914d0c (LOCAL_ONLY) 20050527140332 plugins/Colour functions/Resize2Rotate_.txt
  857b7fee (LOCAL_ONLY) 20071214151302 plugins/Colour functions/Split_Composite.txt
  ec09c233 (LOCAL_ONLY) 20090511134030 plugins/Colour functions/Untitled2.txt
  3273d22c (LOCAL_ONLY) 20070126093526 plugins/Colour functions/Whiten_background.class
  69498417 (LOCAL_ONLY) 20111006142534 plugins/Diffraction_PSF_3D.class
  370eceb6 (LOCAL_ONLY) 20120215130609 plugins/Float_Morphology.jar
  63ecdc2e (LOCAL_ONLY) 20130930211759 plugins/Fret_Analyzer.jar
  d546883b (LOCAL_ONLY) 20110504135416 plugins/Jama-1.0.1.jar
  f3687f76 (LOCAL_ONLY) 20100825151146 plugins/LCS_Reader.jar
  cffa6279 (LOCAL_ONLY) 20140113094418 plugins/LUT_Editor.class
  f67d971b (LOCAL_ONLY) 20060110091750 plugins/List_LUTs.class
  08579b75 (LOCAL_ONLY) 20120315140430 plugins/MBF_menus.jar
  f90ddfd2 (LOCAL_ONLY) 20110311155914 plugins/Macros/plugin1.class
  c32c3597 (LOCAL_ONLY) 20080915152114 plugins/MultiStackReg_.jar
  b9701e7b (LOCAL_ONLY) 20060517093802 plugins/PixFRET_.jar
  12289f6e (LOCAL_ONLY) 20110429093056 plugins/PureDenoise_.jar
  a14102c9 (LOCAL_ONLY) 20100519124428 plugins/QTVirtualStack.class
  4d10572e (LOCAL_ONLY) 20100519124338 plugins/QT_Movie_Opener.class
  0c33d808 (LOCAL_ONLY) 20100519124410 plugins/QT_Movie_Player.class
  a91f4117 (LOCAL_ONLY) 20110214164754 plugins/QuickTime_Capture.class
  617c3507 (LOCAL_ONLY) 20110813165500 plugins/QuickTime_Plugins.jar
  5b80f94b (LOCAL_ONLY) 20100519124502 plugins/QuickTime_Writer.class
  c4a3ace6 (LOCAL_ONLY) 20090415164016 plugins/RC_Montage.class
  5db9a77d (LOCAL_ONLY) 20050509165320 plugins/ROI/Add_Particles_to_ROI_Manager.txt
  970c7851 (LOCAL_ONLY) 20120216143947 plugins/ROI/BG_Subtraction_from_ROI.class
  0118d9a2 (LOCAL_ONLY) 20050426151812 plugins/ROI/MultiMeasure.class
  a76d710b (LOCAL_ONLY) 20050426151804 plugins/ROI/Multi_Measure.class
  3f5cbb5d (LOCAL_ONLY) 20040226102450 plugins/ROI/Select_Half.class
  0bbf33bc (LOCAL_ONLY) 20060110113938 plugins/ROI/SpecifyLine_.class
  6e8dff45 (LOCAL_ONLY) 20041013123544 plugins/ROI/Specify_ROI.class
  8691f4b7 (LOCAL_ONLY) 20080526093216 plugins/ROI/Straighten_.jar
  4112f6ff (LOCAL_ONLY) 20101206235936 plugins/ROI_Color_Coder.ijm
  f1cce332 (LOCAL_ONLY) 20041116151734 plugins/Rocking 3D_project....txt
  2aab7aea (LOCAL_ONLY) 20140605180240 plugins/Smart_Denoise.jar
  b89de656 (LOCAL_ONLY) 20050705225716 plugins/Smoothing/Convolver.class
  73fea577 (LOCAL_ONLY) 20050705225716 plugins/Smoothing/ImageAccess.class
  52a656a8 (LOCAL_ONLY) 20050705225716 plugins/Smoothing/Smoothing.class
  5d221ae9 (LOCAL_ONLY) 20050705225716 plugins/Smoothing/Smoothing_.class
  50a3468f (LOCAL_ONLY) 20120215144327 plugins/SparkMaster_.class
  77bb5c2d (LOCAL_ONLY) 20130124112628 plugins/SpeckleLib.jar
  442cfeb6 (LOCAL_ONLY) 20130124112923 plugins/Speckle_TrackerJ.class
  61d3918f (LOCAL_ONLY) 20110504135408 plugins/Spectral_Unmixing.jar
  42caf3d0 (LOCAL_ONLY) 20050302155648 plugins/StackReg_.class
  d31ed141 (LOCAL_ONLY) 20111207103734 plugins/Stack_Focuser_.class
  d3721d57 (LOCAL_ONLY) 20140604162003 plugins/WalkingAverage_.class
  9a280aec (LOCAL_ONLY) 20120727180330 plugins/absnake_.jar
  a5908c2b (LOCAL_ONLY) 20111207103904 plugins/edf_3D.jar
  bcdea47e (LOCAL_ONLY) 20110502142346 plugins/hdr_.jar
  910c10ae (LOCAL_ONLY) 20061111000356 plugins/ij-VTK_src_0.6/Changes.txt
  19e93b98 (LOCAL_ONLY) 20050704202132 plugins/ij-VTK_src_0.6/Readme.txt
  af7d5c1d (LOCAL_ONLY) 20061110185018 plugins/ij-VTK_src_0.6/lib/ij.jar
  71d9f912 (LOCAL_ONLY) 20061110185436 plugins/ij-VTK_src_0.6/lib/l2fprod-common-all.jar
  f86749e0 (LOCAL_ONLY) 20050701235430 plugins/ij-VTK_src_0.6/test/lib/junit.jar
  4e06a4d7 (LOCAL_ONLY) 20030209120148 plugins/ij-plugins-toolkit.jar
  71331805 (LOCAL_ONLY) 20140708151102 plugins/jacop_.jar
  122cd343 (LOCAL_ONLY) 20061110185204 plugins/lib/ij-plugins_toolkit.jar
  af7d5c1d (LOCAL_ONLY) 20061110185018 plugins/lib/ij.jar
  71d9f912 (LOCAL_ONLY) 20061110185436 plugins/lib/l2fprod-common-all.jar
  f86749e0 (LOCAL_ONLY) 20050701235430 plugins/test/lib/junit.jar