Increased server query response time by 15% by restructuring API
... is that a good example? Increased server query response time by 15% by restructuring API
... is that a good example?"The API latency was 10 seconds, now it's 8.5 seconds."
or
"I reduced the p99.9 latency from 1 sec to 400ms" (by removing input validation)
Your second line is improvement for sure. But it follows the same basic advice to give numbers
However the people deciding if you get hired and what level you get hired at, and the engineering managers who decide if they want you on their team, they understand that it is a bad explanation and care about it. Now there is such a lack of candidates passing the interviews that you will probably get a position anyway, but the position you get might be shit.
Source: I invented the flux capacitor equivalent of the retro encabulator, so should know a thing or two about this!
15% quantifies the Resulting impact of your work succinctly.