Hi, Is this a problem only on my computer or this is some kind of trick to speedup loading next level (loading black screen with yellow words). In my situation when I finish any level fox stuck for few seconds.

For comparision I found few videos. Here, on that one, lag on the end of the level is < 1s:

But here delay i few times longer > 1s:

In my case it's even worst. Any idea how to solve this proble? I try to use DOSbox with 6000 cycles or online game https://www.retrogames.cz/play_711-DOS.php (but this doesn't help).

The game physics freeze until no end-of-level jingle is playing. The trick is: Disable the music by pressing F3 at end of stage. This immediately unfreezes Fox. Then press fire to play the next stage, and, if you like, press F3 again to re-enable the music.

Another method would be to play without music whatsover, by disabling music with F3 in the first level and never re-enabling music. I've always liked the runs better with the music.

In 2017, Covert_Madness, RikusOrs, and I found that disabling music quickens end-of-level, and we all began using it without discussing it much further.

You're right, there is almost no documentation on tricks speedrun.com. Thanks for asking!

-- Simon