Internet Download Manager (IDM) 6.39.2, the mouse movement is extremely slow when downloading something

Internet Download Manager (IDM) 6.39.2, from rapps, the mouse movement is extremely slow when downloading something, and while doing that the log is spammed with

(win32ss/user/ntuser/message.c:946) err: Message WM_PAINT count 22 Internal Paint Set? FALSE

I used the following URL as a test to make the app do a parallel download of 62MB-size:
http://www.boswars.org/dist/releases/BosWars-2.6.1.exe

Expected result
2k3sp2_ok.webm

Observed result
0.4.14-RC-101-g065e47d_affected.webm
0.4.14-RC-101-g065e47d_affected.log