How do you organize Light Room Library

I wonder what is everyone doing with this. Do you have one library which contain all your photos within a specific period of time? Or do you have individual library for each event you shoot? I don't know what is the best way to manage LR. I used to use ACR, didn't have to setup library.

I have one library for all DSLR photos, and a second library for all photos that were taken prior to that on digital P&S cameras. The DSLR library has about 52,000 photos in it thus far. Within that library, I navigate by folder with one folder for each event I shoot. Works fine for me thus far.

When the library gets this large, does it become very slow?

In my case, I have about 2000 raw file in my current library, kind of slow when starting up LR already. I was think of creating individual library for each event I shoot. Does this make sense?

I don't really think about it much, as I have two computers on my desk and one of them is used almost solely for Lightroom. It takes some time to start it up, but after that it's fine. Unless I need to select "All Photos" and do something to all of them at once, of course. I know others are using libraries with well over 100,000 photos.