Server version plays a lot into the XPages light-vs-heavy discussion. E.g. 8.5.0 didn't auto-flatten Dojo files. If you enabled the calendar control on a date field you'd end up with 50+ JS hits as it pulled in the various Dojo files. 8.5.1 auto-flattens the files, resulting in just a few. But it doesn't auto-flatten the CSS. Supposedly they tried to get that in to 8.5.2 but couldn't, so perhaps it'll be in 8.5.3.
Server version plays a lot into the XPages light-vs-heavy discussion. E.g. 8.5.0 didn't auto-flatten Dojo files. If you enabled the calendar control on a date field you'd end up with 50+ JS hits as it pulled in the various Dojo files. 8.5.1 auto-flattens the files, resulting in just a few. But it doesn't auto-flatten the CSS. Supposedly they tried to get that in to 8.5.2 but couldn't, so perhaps it'll be in 8.5.3.