Recently I have noticed that when there is a cursor change when moving between controls some "lag" occurs. It is not seen when you have static scene (or when you change it only via tweak bar), but when there is a smooth animation underneath it can be painful.
Workaround - not a solution - is to disable the cursor changes.
Fortunately in the code we can find:
// TwMgr.cpp, line 86
#ifdef ANT_WINDOWS
bool g_UseCurRsc = true;
// use dll resources for rotoslider cursors
#endif
Just set it to false, rebuild and it should work! No stalls occur in my apps right now.
You can see the code here on the sourceforge repo page.
Title image based on image from the library page: anttweakbar.sourceforge.net/doc/