uBlock Simple is a close variation of uBlock Origin. Currently the only difference is that the popup UI contains a global switch on/off button, instead of a whitelist-site button -- catering to users who prefer to use a global switch instead of whitelisting sites.
The source code can be found at https://github.com/bigicoin/uBlock (forked from uBlock Origin).
This extension is not any faster or slower than uBlock Origin in terms of performance. There is no additional features, no additional tracking. Literally the only difference is the switch button.