Mysterious Slowdowns

While making a hero system for an RPG map i'm working on, I found that currently, whenever a hero unit is created, swapped into the game via replace etc, the game freezes for a short period of time (about 10-15 secs).

I have no idea what the reason for this is, and as far as I can see, the problem doesn't lie in my triggering (it does literally only happen when a hero is created), but one of the causes may be the large number of abilities the heroes have (at LEAST 18 - with 3 spellbook-based menus), but as I say, i have no idea... It's happened before though, in another map of mine, with a hero which had only 7 abilities

If anyone else has encountered this problem and solved it, i'd love to hear how it was corrected, as it's really giving me a headache

Solution: Create every type of hero instantly at Map Initilization; then remove them after .01 seconds of game time. This way the game will have already loaded the Hero types from the Object files.