Maestro file become very large

I have been accumulating tests in one maestro file (45MB).
It is taking quite sometimes to open and do simulation, especially when using Run Plan.
I thought it is just like that because I put so many tests, global variable, parameters, etc.

Today I made a new maestro file and imported all the setup from the old maestro file.
It turns out the new file is way smaller, less then 1MB.
The new maestro do not have Run Plan from the previous file, I do not know what else is missing.

Is there any way to reduce the size of the old maestro?
or maybe a way to check why the size becomes so large.

I use IC6.1.7-64b.500.15