I am able to sync my firefox and chrome bookmarks, and it's syncing speed is also fast. I recommend this extension (free one) to everyone who is using multiple browsers on multiple devices.

EXCELLENT +++! simple, fast, efficient

Synchronization between cross browsers, cross browsers and devices,
and you can also use your favorites from the web, after logging in, in this way you always have them updated, synchronized and you can use them anywhere.

Perfect presets, simple and very productive.

Installed and tested, on Chrome and Firefox, and I have many favorites:
it works perfectly!!!

Mozilla should consider including it in the Firefox suite, losing some ownership of the product, but significantly increasing the quality.