I'm under the impression that Savitar is a regular speedster with regular speed, but somehow gets an incredible boost from alchemy. However, using the extra speed may be detrimental to his health, which is why they were creating other metas to do their bidding. I believe that Julian as alchemy may not truly be a villain, but is being forced to help savitar as alchemy himself isn't much of a match for a speedster.

This explains why Julian hates metas (he's being controlled by one), and why savitar is the one who kills rival for failing and scratches "alchemy" into the wall. I think that savitar is trying to use misdirection to trick people into thinking that Julian wants to be a villain.

Savitar is also probably directly connected to the speed force, which is why he actually hasn't killed barry (though it would be easy for him). Without barry, the speedforce would be lost. This is why killing the flashes mother trapped the RF in his time, because without the flash, there is no speedforce.