D.C - D.C converter

To what percentage level?

99% of the charge voltage will be there in the time represented by the capacitance multiplied by the supply impedance multiplied by 5.

http://en.wikipedia.org/wiki/Time_constant

Shuffle feet on carpet

Ouch! That hurt!

RC charging is usually slow and very inefficient. What is your capacitor value?

The resonant inverter style power supplies designed specifically to quickly and efficiently charge capacitor banks and pfn's are your best bet. Some examples here...

http://www.us.tdk-lambda.com/hp/product_html/high_volt.htm

It all depends on the value of the R and the value of the C. Don't forget that unless your wiring uses only superconducting material you will always have a non-zero value for R.

RC charging puts 50% of the energy into the capacitor and 50 % into the resistor and is time limited by the RC time constant (typically 3 to 5 RC seconds). Switching and resonant chargers use reactive elements to transfer the energy to the target capacitor. Obviously never 100% efficient, they can exceed 90% efficiency and can also reduce the charge time by an order of magnitude or more.

If the OPs capacitor is large and the short charge time is critical, then the added expense of a resonant charger may be justified.