In addition, an important concept in Qspice is TTOL in logic device, which is useful in simulate switching circuit. This is a post discuss about TTOL.
TTOL device to Interface analog and digital - QSPICE - Qorvo Tech Forum
In general, using TTOL device (includes TTOL in .DLL C++ block) can help to reduce simulation time as compare using maxstep, and in certain situation, the improvement is huge (but not in your case, only 20% reduction of simulation time).
Here is a comparison with maxstep and ttol approach. I modified your comparator library path to MyLibrary.txt, so that I can run your simulation only copying everything into a same folder, which is better for sharing purpose. As forum not support .lib to upload, I use MyLibrary.txt for everything.
3.- Buck-analog-control-open-loop-bode - Maxstep.qsch (11.1 KB)
3.- Buck-analog-control-open-loop-bode - TTOL.qsch (12.8 KB)
MyLibrary.txt (657 Bytes)
