Who cares about efficiency, I have 8 GB RAM and|or a quad core CPU - uBlockOrigin/uBlock-issues GitHub Wiki

Doing more with less is a virtue in software. For users of uBlock Origin (uBO), this means:

  • Less CPU churn when loading a web page may translate into a noticeable faster page load.
  • Higher memory consumption correlates with higher CPU-cycle consumption. Any extra memory used is the same that needs to get allocated/written to/read from (at least once)/garbage collected.
  • Free to use more filter lists:
  • Longer battery life. Each time unit, however small, that the CPU is idle rather than churning translates into extended battery life.
  • Free to use a blocker on less powerful devices
  • Free to add more functional features
  • Free to use more extensions

Memory and CPU cycles are finite resources. A sure way for a developer to not get hired when being interviewed is to dismiss efficiency work because "memory is plentiful" or "CPU nowadays are fast enough".


"Come on people, we are buying our hardware precisely for this - to be used" [source]

Wasting is not using.


Not convinced yet? Try using a stopwatch to compare how fast web pages load when using one blocker compared to another.

If you have a multi-core CPU with plenty of spare CPU cycles, you may not notice a difference in page load. Other popular blockers will use any available CPU cycles (see below) to perform the same job as uBO.

CPU overhead CPU overhead

Memory footprint Memory overhead