You should use the Radioactivity module
This module provides a field type which can be used as a hotness metric or a regular view counter for entities and for much much more. In essense, entities receiving attention (views or actions defined by Rules) are heated while inactive ones slowly cool down.
You can add an 'emitting' field to any entity (including a profile2 entity), and the module can be configured to do basic page counts without the decay profiles if you don't need them.
As it's a field, you can use it in Views as normal for sorting.
It has several storage options (some of which do not relay on the database), integrates with memcache etc, so it doesn't have the same performance problems as the core Statistics module that Letharion has mentioned.
Make sure you read the instructions though, it took me a while to realise that the statistics won't be counted unless the field is actually displayed on the entity type in question (not just attached to it, it needs to be visible in 'Manage Display' - nothing will be printed to the screen but it needs to be there for the stats to be counted).