mysql 5 vs 5.5 memory usage I had a less less memory usage in mysql 5 vs 5.5 do they do something drastically different? I went from around 100mb to about 1 gb of memory usage.

Does memory usage in 5.5 also grow over time?
I don't know exactly if 5.5 require much memory than 5.0 but look this example : 

In 5.0 MySQL Official Documentation:

innodb_buffer_pool_size : The default value is 8MB.


In 5.5 MySQL Official Documentation:

innodb_buffer_pool_size : The default value is 128MB.


If you paste your both "show global variables" results (5.0 and 5.5) we'll can see exactly what variables have gone up...

Max.