I imported a few photos, it worked. I tried to import the ones I tried earlier, and it's not working very well. Taking a long time. There are a bunch of videos, I'm trying to import them so I can free up some space on my phone.
Why would it work better in a new library and now the one I normally use?
Because there's something wrong with the main library?
If there are a lot of videos then it might well take tim, as videos are larger files.
Back to the original library:
Back Up and try rebuild the library: hold down the command and option (or alt) keys while launching iPhoto. Use the resulting dialogue to rebuild. Choose to Rebuild iPhoto Library Database from automatic backup.
If that fails:
Download iPhoto Library Manager and use its rebuild function. This will create a new library based on data in the albumdata.xml file. Not everything will be brought over - no slideshows, books or calendars, for instance - but it should get all your albums and keywords back.
Because this process creates an entirely new library and leaves your old one untouched, it is non-destructive, and if you're not happy with the results you can simply return to your old one. .
I have spent months with this problem and FINALLY found out the relatively simple culprit and solution after talking with very helpful apple support people by phone (free live phone support is apparently available after upgrading to Mavericks).
The problem wasn't with iphoto. The problem was not having enough RAM to allow iphoto to do its thing. When plugging in my phone to import photos, it pushed my RAM capacity past its limit, which caused the endless spinning wheel and the computer freezing. In particular, scrolling through iphone thumbnails seemed to trigger the crashing.
To determine if this applies to you, you can open the Activity Monitor utility and click Memory tab at the top and then look at Memory Used -- if the amount of Memory Used is anywhere close to Physical Memory (available), then RAM could be the problem.
My IMac is only a few years old and came with 4GB RAM standard, but that apparently isn't enough nowadays unless you close everything else. Skype and Itunes were opening automatically and running in the background, eating up lots of memory. Obviously you can try and manage RAM by stopping those from opening automatically, etc., but regardless, I'm going to purchase more RAM.