(disclaimer: I work for Opera) This year Opera has had a lot of focus on performance tuning under the umbrella of Power Saving Mode that was shipped in Opera 39. It was many small optimizations like for example reducing timer frequency in unused tabs or UI animation fixes as well quite advanced memory compaction that is now being upstreamed (https://groups.google.com/a/chromium.org/forum/#!topic/blink...). Recent Opera 42 features a small but nice update to startup p/restart behaviour - it schedules only the most important/recently used tabs for reload right away - which is quite useful for people like me who normally have dozens of tabs open all the time.