Hi ali samad and welcome to our community
You probably aren't going to like the answer. But here it
goes.
Don't record everything in full motion! Captivate was never
engineered to be a totally full motion capture tool. As you have
seen, there are performance issues.
If you record using the method intended, by allowing
Captivate to grab screen captures, then later stitching them all
together with mouse movement and other objects, you should still
end up with a decent presentation and it will be much smaller and
more efficient.
Cheers... Rick