I've tested 32-bit versions of - 5.0.2.2 (https://downloadarchive.documentfoundation.org/libreoffice/old/5.0.2.2/win/x86/LibreOffice_5.0.2.2_Win_x86.msi) - 5.0.2.1 (https://downloadarchive.documentfoundation.org/libreoffice/old/5.0.2.1/win/x86/LibreOffice_5.0.2.1_Win_x86.msi) - 5.0.1.2 (https://downloadarchive.documentfoundation.org/libreoffice/old/5.0.1.2/win/x86/LibreOffice_5.0.1.2_Win_x86.msi) on Window$ 7 Ultimate SP1 x64 where I uninstalled each version and renamed §%APPDATA%\LibreOffice§ before installing another version. Of the tested versions, only 5.0.2.2 suffers from this issue, others display absolutely no performance degradation as far as my quick testing (start LO, open Calc from the main menu, click a few cells, move mouse around the menus quickly and open the settings window) went. I've only tested British English and Finnish GUI languages but it didn't make that much difference although British one gave a little faster performance.
Not producible on 5.0.3.2 x64 on Window$ 7 x64, so it was fixed way or another in some version.