The question is simple: How do you load custom UITableViewCell from Xib files? Doing so allows you to use Interface Builder to design your cells. The answer app
If you're using Interface Builder to make cells, check that you've set the Identifier in the Inspector. Then check that it's the same when calling dequeueReusableCellWithIdentifier.
I accidentally forgot to set some identifiers in a table-heavy project, and the performance change was like night and day.