Sounds inspector very slow on PC

I have an app that has maybe 1000 sounds in its library. Some are called via actionscript and linkage, but others are just attached to the hit frame frame of a button, then the sound selected from the drop down list in the properties inspector.

My problem is that after you click the drop down list (to select a sound), you have to wait an eternity!

I had this problem a year ago on a different PC, but curiously, it didn't happen on my old macbook pro 2011 (which being older and slower, otherwise struggled to run animate well).

Recently, I upgraded to new high spec laptop, and figured that the lag would be cut down (if not eliminated).

However, it's only gotten much worse! In fact, the wait is minutes - i.e. totally impractical.

No doubt the problem is partly due to having so many sounds in the library (i.e. if i create a new app, with just a few sounds, there is no lag). However, the fact that it's only a PC thing suggests that animate shouldn't be doing this.

Anyone else had the same trouble, or know a fix?