chore(performance): remove class interpolation and do manual add/remove ...

One step forward into improving the grid performance. 

By using Chrome CPU Profiler I noticed that there was a lot of time spent on Attributes.$updateClass, which refers to interpolations on an $element class attribute. After removing some class interpolations am seeing a 15-20% performance increase but am doing manual profiling.

Any way to automate the profiling and getting average values from multiple runs?