I've got some additional details. Using the old VM at: http://files.pharo.org/vm/pharo/win/Pharo-VM-win-stable.zip I downloaded a fresh 50491 image at:http://files.pharo.org/image/50-preSpur/50491.zip Opened a playground and executedImageCleaner cleanUpForProduction This was really fast, and in 2 minutes the process was complete. Then I downloaded the 50492 image at:http://files.pharo.org/image/50-preSpur/50492.zip Did the same ImageCleaner cleanUpForProduction, only this time is took about half an hour to do the same. Hope that helps to catch the reason.Thanks On Friday, February 5, 2016 9:33 AM, Maximiliano Tabacman via Pharo-users <pharo-users@lists.pharo.org> wrote: Thanks for the reply Marcus.I just checked, and can confirm that the old process took only 2 minutes and converted a 58,2 MB image (includes Seaside and my web product) into a 26,4 MB production image. By looking at PharoDebug.log, I can tell that this version is: VM: Win32 - IX86 - 6.1 - NBCoInterpreter NativeBoost-CogPlugin-HolgerHansPeterFreyther.21 uuid: e0df6e2d-5694-40e2-8035-dc217200b424 Sep 25 2014NBCogit NativeBoost-CogPlugin-HolgerHansPeterFreyther.21 uuid: e0df6e2d-5694-40e2-8035-dc217200b424 Sep 25 2014https://github.com/pharo-project/pharo-vm.git Commit: 81b5d19917dcb78f22482a780deec48c53738396 Date: 2014-09-20 14:36:18 +0200 By: Esteban Lorenzano <estebanlm@gmail.com> Jenkins build #14858Image: Pharo5.0 [Latest update: #50491] Hope that helps. This is Pharo 5, so the Image Cleaner must have broken at some point after this version. Let me know if there is any additional information I can provide to help figure it out. On Thursday, February 4, 2016 12:22 PM, Marcus Denker <marcus.denker@inria.fr> wrote: Hello, Sorry for the late answer. I think there are multiple problems… 1) slowness. This is strange that unloading packages is so slow. This looks like a bug to me. 2) image size in Pharo5: We have a bug right now that images *never* shrink. This means that if you savean image once with 80MB, even if the GC cleans up, the saved image stays 80MB. We should fix both…. On 25 Jan 2016, at 13:32, Maximiliano Tabacman via Pharo-users <pharo-users@lists.pharo.org> wrote: From: Maximiliano Tabacman <mtabacman@yahoo.com> Subject: Image Cleaner no longer useful? Date: 25 January 2016 at 13:31:28 GMT+1 To: "pharo-users@lists.pharo.org" <pharo-users@lists.pharo.org> Reply-To: Maximiliano Tabacman <mtabacman@yahoo.com> Hi, and sorry if this has already been discussed. In Pharo 3, I used to be able to do: ImageCleaner cleanUpForProduction and that would correctly remove a lot of unneeded code in the image when preparing for a productive release.Then I would save the cleaned image, and since it had been cleaned, it would be smaller than the original development image (say from 60 mb to 25 mb).This process would take about 2-3 minutes. Then, in Pharo 4 it seems some changes were made here, since the same process took a lot more, like 20 minutes. When I first tried Pharo 5, I was happy to see that it was again down to 2-3 minutes. And here comes my question...Why is it that since some 2 months ago (maybe more), the Pharo 5 images once again require like 20 minutes to complete the cleanUpForProduction process? Also, and this is the most relevant to me, it no longer reduces the image size.So if I want to release a Pharo 5 version based on the latest images, I would be shipping a product that is more than twice the size of previous public versions of my software! Thanks for any insights into this. If it is a known bug, I would like to know if there is any workaround, or alternative objects that I should be using for the process.Also, if it would help for me to run any tests in particular to share and help in fixing this, please let me know.