If you have any CC I'd merge your package files, and convert any sims3pack files you can into package and merge them too (this made the most significant difference in my wait times, especially limiting my sims 3 pack installs to only lots I can't live without or store content). One note on the packs though, sets containing counters in sims3pack form don't convert well, so anything containing a CC counter set needs to be left in sims3pack form.
The thousands of excess items are probably not that great either, since it's often recommended that your inventories be kept light as possible. My advice on the alchemy ingredients for now would be to look up what the highest level ones you can make between your current rank and max level and only keep the ingredients you'll need to finish up.
For the hanging it might be a good idea to make sure your graphics card can handle the game: I plan to upgrade mine later in the year because I realized for the amount of stuff I'm cramming in my game my card is actually too weak for it.
http://simswiki.info/wiki.php?title=Game_Help:TS3_System_Requirements
I also found that a lot of my problems were eliminated once I started using a batch file to clean up my sims 3 folder every time before I played. If you want I can upload it for you, though someone here posted a guide on how to make your own.