Hello, if i will repair sketchup program, will i lose already installed plugins?
No. The extensions are installed in a user area, not with the Program Files.
Daver Thank you very much. i have problems about thumbnails. i use SU 2020, 2 weeks ago i downloaded SU 2017 make because it is free version. i got it because i thought i use Su 2017 for render, in Su 2020 i have installed many plugins and in my mind in Sketchup 2017 without plugins it may worked more well. i just wanted to test it. but after i installed Su 2017 i can not see thumbnails. after this i uninstaled 2017 version, choose 2020 as default app again but thumbnails are hidden again. i tried many ways but no, they did not work. so i decide to repair it maybe it will help.
Try repairing the 2020 installation or, at this point you might as well update to 2021. Installed extensions shouldn’t have any impact on your rendering program. In most cases rendering speed is going to be determined by your CPU’s capabilities. SketchUp itself isn’t really doing anything special while the renderer is busy.