I need to optimize the RAM usage of my application.
PLEASE spare me the lectures telling me I shouldn't care about memory when coding Python. I have a memory problem because I use very large default-dictionaries (yes, I also want to be fast). My current memory consumption is 350MB and growing. I already cannot use shared hosting and if my Apache opens more processes the memory doubles and triples... and it is expensive.
I have done extensive profiling and I know exactly where my problems are.
I have several large (>100K entries) dictionaries with Unicode keys. A dictionary starts at 140 bytes and grows fast, but the bigger problem is the keys. Python optimizes strings in memory (or so I've read) so that lookups can be ID comparisons ('interning' them). Not sure this is also true for unicode strings (I was not able to 'intern' them).
The objects stored in the dictionary are lists of tuples (an_object, an int, an int).

my_big_dict[some_unicode_string].append((my_object, an_int, another_int))

I already found that it is worth while to split to several dictionaries because the tuples take a lot of space...
I found that I could save RAM by hashing the strings before using them as keys!
But then, sadly, I ran into birthday collisions on my 32 bit system. (side question: is there a 64-bit key dictionary I can use on a 32-bit system?)
Python 2.6.5 on both Linux(production) and Windows. 
Any tips on optimizing memory usage of dictionaries / lists / tuples?
I even thought of using C - I don't care if this very small piece of code is ugly. It is just a singular location.
Thanks in advance!
For a web application you should use a database, the way you're doing it you are creating one copy of your dict for each apache process, which is extremely wasteful. If you have enough memory on the server the database table will be cached in memory (if you don't have enough for one copy of your table, put more RAM into the server). Just remember to put correct indices on your database table or you will get bad performance.
Python tips for memory optimization