I recently got a used DL360 g6 server on my hands.
It has 2 5670 CPUs with 12 cores and 24 threads, and came with 80GB of RAM.
Windows OS runs pretty fast on it, but linux distros are terribly laggy on it. for example, clicking on menu to open terminal takes almost 1 to 10 minutes on different Linux Distros, the slowest is CentOS which I need to install. No problem without GUI at all and everything works smoothly without GUI.
I realized the hardware doesn't support higher resolution than 1024x768 but my linux distros all run in 1920x1080 @ 60hz. I tried to reduce resolution (it took almost 1 hour open display settings to reduce resolution!), I noticed speed boost compared to default settings, but still unusable at all.
What should I do to use GUI without lags? How can I fix the problem?
Edit: lspci show following VGA controller which is onboard:
VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] ES1000 (rev 02)
Note that GUI on installation process doesn't lag at all.