I made a change in Chrome, but changes only appear in this app after I manually sync. Why doesn't it auto-sync?
Unfortunately the auto-syncing is not "real time". By default, Android performs an auto-sync once every 24 hours. Obviously you can check again by manually forcing a sync, but normally android will perform it
24 hours after the last time mentioned in the android "Accounts & sync" screen.
This is because the protocols needed for bookmark sync haven't been optimised by Google for mobile usage. It takes a lot of data to perform a check and, as you see each time you perform a sync, it does take a good few seconds and maxes out your cpu at the same time. If it did this regularly (i.e. every five minutes) you'd notice a huge increase in your data usage and your phone would keep hanging while performing the sync.
Google knew people would want real-time email and calendaring, so they re-wrote those protocols to be considerably lighter and better suited for mobile usage. They then make their apps override the auto-sync default and poll once every few minutes. Since they optimised it to be literally a couple of bytes, it's much quicker and painless.
They never originally envisaged people using Chrome bookmarks on a mobile, so they haven't done any work to make it slicker/quicker. There may be some optimisations in Honeycomb/ICS, but (a) there are many bug reports that Honeycomb/ICS doesn't work anyway and (b) the source code has not been released to the public so I cannot take advantage of it.
Annoyingly, Android doesn't make it clear that a default "Accounts & sync" entry syncs once every 24 hours - this is because most users see GMail and Calendar and Contacts in there and Google overrides all of them to sync semi-real-time. It still does a full refresh once every 24 hours, but you don't normally need that full refresh.
I've got a request on the community website to allow users to override the default sync frequency ( here ). But no votes for it, yet.