Why the heck would you have that many entities...
Did you never try running the game prior?
What are they... blades of grass?
Painkiller is right... you can add a line of code with the number of entities max value. You can also do that for particals...
If you have that many entities and they each are fairly large files like say trees at even a quarter meg each... you are going to really run at a slow frame rate.
That is why I have run-time trees that show up where you look and are removed from memory where you no longer look...
If you give a little bit more description... maybe we can help better.
G'd luck...