How would you know if a reaction is faster than another? Does it have to do with stability, Such as that the reaction would be slower if the molecule is very stable (mainly when a compound is branched)? Or is it only related to primary, secondary, and tertiary; where primary is the fastest and tertiary is the slowest? (Lower energy difference  between a starting compound (intermediate) and the transition state  (activation energy) at the rate-limiting step makes the reaction sequence faster. - GS).