When in a party, the experience from mobs is calculated as an average level within your party - not each individual's level. So if you're doing RFC with 4x Level 12's and 1 Level 60, your average char level would be calculated as L22, so you get pretty little exp per mob, but hope to make it up in speed. Once you get into the SM/ZF/Mara range, the level difference doesn't impact you as much.

See this thread to see the exact experience per mob by level. https://www.dual-boxing.com/threads/...b-EXP-by-Level