@stevencee if you haven't already I would enable the one-click keyboard shortcuts. Better usability imo. Press 0 or + (repeatedly if desired) to zoom in and then 6 to return immediately to 100%. Far easier than messing around with the icon.
Same here (debian testing x64, opera 54, openbox, no compositing), with opera's hardware acceleration disabled or enabled.
If feels a bit faster when using ctrl and +/- instead of ctrl and scroll wheel up/down.