the sound is no problem, but more depnding on the size of the maps you use.
big maps needs loading time, as well to mention, there are some audio plugins
to add dynamic sounds and or resolve this sound so it plays correctly on any
map size you use.
as for the 1 min duration, I canot tell, or big maps, but some has mentioned delay's.
while it doesn't happen to me (yet), it can still happen, but I have an high end
gamings computers, so it run better than people that uses average pc or below
which can happen more often (probably) with sound issues.
you need to think carefully what music you use, and if a plugin is needed to avoid
the delay of it in case it happen.
same thing happens when showing pictures or flicker, the reason of this, and
also possible in any engine you use is that those aren't loaded yet, so the delay
will be there.
there are preloaders plugin or load images, sounds before the maps is fully loaded
in order to avoid any delays.
I think every engine might have this. MV load presets when needed and cache it than,
and most times, this need to be done BEFORE you enter the map to avoid any delays.
So far I haven't encountered such problem, and I use custom music too (2-3 minutes).
As @ShadowDragon said, it might be the case of hardware performance
(but I use 9 year old laptop and never encounter such issue).