[Taska]

It could be hard to say exactly what causes this without a bit more detail of your problem.
Are you actually looking at the explosion when it happens? If it's a bomb exploding behind you
and you're not looking at the explosion/damage then it's probably not a graphics issue.

A lot of people ignore the fact that audio processing is quite intensive too and without a decent
soundcard (decent soundcards do not include anything by Creative, i.e. Audigy etc and anything
"onboard" is a definite no-no) your sounds can add quite a load. Especially if you're using new
sounds which can be significantly bigger files.

This is just one idea, it may be the load of calculating the damage done, new dead meshes
or any number of possibilities. Try to work out in what circumstances the pause happens.
What you're destroying, are you looking at it, has any part of it been modified. It may turn out
to be easier to find than you think.

Good luck