Dramatic high dwm GPU usage when running Fences

Hi, I have been using Fences for about one and a half year.

About 9 months ago, I bought a 4k resolution display and use it as a secondary display. A really frustrated problem on 4k screen that always bothered me is that the running of some big-windowed application result in a very seriously stuck. Sometimes it crashes the apps like madvr or vncviewer.

Then I tried to monitor the status, found that when all these happened, the usage of Integrated GPU (i7-4720HQ) would be over loaded. The load will sustains at 100% until I close that app off. I tried many ways to fix it but none of them works. Until 1 hour ago, I started to disable every desktop enhancement apps off one by one. And, yes, after I uninstalled Fences, everything goes back to normal. No matter what I do, the usage of GPU keeps lower than 30%. After reinstall Fences, the stuck comes back again.

All I know now is when Fences is running , and the size of the window is wider than 2560px or higher than 1440px on the secondary monitor, would result in that stuck or lag. The problem process is dwm.exe(desktop windows manager), the usage of GPU by this process will exceed 50% if the window is larger than 2560*1440. And if it is wider than about 3200px, the usage of GPU will be sustains at 100%.

Is it just me or anyone else have same problem?