Your sampling efficiency against the top samplers, and the best setup for each activity from your whole account.
Gain × is your total efficiency with that single source raised to the best top sampler's value, divided by your efficiency today. Sources that sit in the same additive group share one multiplier, so their gains do not simply multiply together.
Efficiency is not yield. In the game's fishing formula, items per action grow with efficiency to the power of about 0.35 once prowess is capped at 0.1, so 10× efficiency gives about 2.2× items. Mining, chopping and catching very likely work the same way, but that is not verified.
Top samplers are the characters holding each account's best Copper, Oak Log, Fly and Goldfish sample, read from their public IdleonToolbox profiles on . Their character-specific values (talent levels, skill level, stats, star sign, prayers) are from their current loadout, which may not be the one they sampled with.
Calculations use IdleonToolbox's own parser, bundled into this page (GPL-3.0, github.com/Morta1/IdleonToolbox). Your save is processed in your browser and is not uploaded anywhere.