WTV conversion to h264 - improve seek/skip?

How can we improve skipping in Windows Media Center?
I have recorded those files in WTV (MPEG2 and some h264) format from cable TV.
I have reconverted them to WTV h264, using hardware encoding (nvidia Pascal nvenc), with the purpose of reducing the size.

Well… everything is fine, I have applied -50% quality from the default profile and the size decreased indeed.
But now seek/skip takes longer. Instead of being approx instant (original files) now it takes good seconds.
Is there any solution to that?