is precomp.dll a windows file, because when I was trying to install something, the program stalled, and precomp.dll was taking up to 25% of CPU usage, is this malware or just windows doftware already installed on my computer.

precomp.dll is part of lprepaq, itself core files for precomp.

Precomp is a precompressor, and it might be used in several software, as a compressing tool, and is not unsafe by itself.

Nevertheless, precomp.dll is found in multiple games downloads, where it is advised to delete it, as it only is left over from the compression of these games, but is very often related to downloading such games from torrent and/or warez, leading to think that, if whatever security threats exists, it is not with precomp.dll itself, but with the other downloaded files.

It is definitely not related to windows.