From what I've experienced/read/etc...
Dwell is the amount of time the solenoid is in the "on" position. The higher the dwell, the lower the efficiency, but the gentler on paint, and the lower the chance of FSDO.
An improved hopper is just going to make sure you have a ball in the breech every time you pull the trigger.
A DYE UL barrel is going to provide a smooth, honed surface for the paint to be launched out the breech.
As Matrix stated - nothing you've changed should impact your dwell.
Now - as it gets colder, if you wish to play outdoor, you may have to increase your dwell, as colder internals and colder lube won't move or seal as well. In that situation, a thinner lube, and an increased dwell may help the marker cycle properly....reducing bolt-stick and FSDO