We tested how Mecha Face's boost and the short circuit ball after an odd occurrence last session and found that it can decrease his run speed to 365 (tested when boost was at max, meaning previous speed was 520). It was also found that you can get your boost back normally by getting more kills. We did not test this with other energy-based weapons. This is the only instance I found of Mecha Face's boost being decreased outside of deaths.

(this might have to do with how energy weapons are modified to slow down robots?)