uBOL is entirely declarative, meaning there is no need for a permanent uBOL process for the filtering to occur, and CSS/JS injection-based content filtering is [performed reliably](https://developer.chrome.com/docs/extensions/reference/scripting/#method-registerContentScripts) by the browser itself rather than by the extension. This means that uBOL itself does not consume CPU/memory resources while content blocking is ongoing -- uBOL's service worker process is required _only_ when you interact with the popup panel or the option pages.
uBOL does not require broad "read/modify data" [permission](https://developer.chrome.com/docs/extensions/mv3/declare_permissions/) at install time, hence its limited capabilities out of the box compared to uBlock Origin or other content blockers requiring broad "read/modify data" permissions at install time. <details><summary>**However, [...]**</summary>
uBOL allows you to *explicitly* grant extended permissions on specific sites of your choice so that it can better filter on those sites using declarative cosmetic and scriptlet injections.
The browser will then warn you about the effects of granting the additional permissions requested by the extension on the current site, and you will have to tell the browser whether you accept or decline the request:
You can set the default filtering mode from uBOL's options page. If you pick the Optimal or Complete mode as the default one, you will need to grant uBOL the permission to modify and read data on all websites:
