Please pick one specific action you'd like faster (the one that bothers you most), and start a thread with details on how to reproduce the slowness. Mail a library backup to logs at jriver dot com, so we can test the same on our side.
We might be able to help.
You said "pick one", but there are two I'd like to mention. With my current library the two things I find I'm waiting the most for is:
-Changing the view from video to audio or changing views within the audio section. This is essentially the same action I guess.
-Doing a search within the audio section.
Both these thing take maybe around 2 seconds on my machine. This is by no means worthy of criticism considering the size of the library, which is now at 546 250 files, but Matt wanted me to create this thread so I'm just happy to oblige :-)
In the thread I'm quoting I posted my JRMark score and it was 4364. This is on an Intel i7-3770K sitting on an Asus P8Z77-V PRO with 16GB of DDR3 RAM from Corsair at 1600Mhz. The library, MC and the OS (Win8 8.1) is on a Samsung 840 Evo 500GB SSD.
I will mail the library backup as requested using the same subject as this thread.