Maximum power for a 12V solenoid
If you need a faster and more powerful stroke, you will have to go for higher voltage. The capacitor-resistor addition is there to reduce the current after the initial stroke to reduce power dissipation and maybe improve release time and maybe allow it to remain engaged longer.

This is a nice answer about driving solenoids faster: https://electronics.stackexchange.com/a/295529/26987
It shows a schematic of an elaborate driver and explains in text why it is so. But basically the idea is the same: more power comes with higher voltage and therefore current.