I'm planning to compress my iso images with linuz iso plugin to save some disk space and i have a question. Is there a performance difference between running games with compressed and non-compressed iso images? I thought running a game with a compressed image affects cpu performance and i don't want to lose any fps.
It will be slower at times, but I haven't seen actual speed comparisons. Also, if slower on your specific case/s means 130% speed instead of 150%, or mostly slower load times, then it might not matter much. You'll have to test for yourself.
Also, you can use Windows folders compression instead. The compression ratio will only be slightly worse than Linuz Iso, but performance will probably be better because of the file system cache of windows.
Games are not constantly loading data so the performance loss will be minimal at best, unless you're using like a netbook or something with very very slow cpu/disk performance to begin with
If your CPU isn't running at 100% already when you're playing, it will have unnoticeable speed loss (talking about 1-2%). (it'll require additional CPU resource to decompress the data).
If it is already running at 100% when you're emulating, I wouldn't compress the isos.