Will a dropped ball compress faster than it decompresses? I'm modelling how a ball's compression changes over the duration of an impact. However, I'm not sure if on the physics behind the compression/decompression rate...
Or would decompress at the same rate it compressed?

Would the ball decompress slower than it did to compress as it has lost some of its energy in the collision?

 A: It will take more time on the rebound. If the ball loses energy, this means that after the rebound, just off the floor, the ball is going slower than when it arrived. To go slower, it means that it is accelerated less on the rebound than when it arrived. In other words, at each compression level, the acceleration (in absolute value) is smaller on the rebound than it was when the ball arrived. Smaller acceleration at all compression value will translate in a longer time to "undo" the compression than it took to do it. 
A: I agree with the answer from @ManuelFortin
In addition, the reason for the slower decompression is elastic hysteresis.  As explained in the article, materials don't quite obey Hooke's Law, which states that the force generated by a compressed material is only a function of the material stiffness and the deflection.  For example, a rubber band has lots of elastic hysteresis as shown by the following example loading/unloading curves.

Image By Johannes Bedenbender et Tiger66 - Own work of Johannes Bedenbender on Wikimedia Commons, CC BY 2.5, Link
