Surprisingly, this situation has come up a number of times.
 
I have a MIDI track I want to use in another song.
 
The MIDI track is 8th notes.  In the new track, it needs to be 16th notes.
 
I can do a find/change to convert all the values, but then there are gaps in-between the notes and it is quite tedious to move each one.
 
How could one easily change 8th-8th-8th-8th to 16th-16th-16th-16th?  In other words, this would effectively make the MIDI track twice as fast.
 
Note that all the notes may not be 8ths—I just used that to illustrate.
 
Thanks.

It would depend on the material but you could open clip in PRV, select all the notes, Process-> Length, have start times and durations checked and set to 50%. Then copy paste to make it the same length as before.

Yep Process->Length works perfectly. I use it a lot.