Well, to be more precise:

1. MicroB application is a thin shell that uses browserd for everything, including rendering and JavaScript. By itself, this application does not crash very often as it does not do much work.

2. Gecko is a rendering engine rather than a browser. It runs inside browserd and handles HTML and CSS rendering. My guess is that it is responsible for a half of all problems (especially with CSS).

3. In addition to Gecko there is a JavaScript engine also running inside browserd. It is probably responsible for another half of the problems.

4. Finally, there is code responsible for loading and caching web pages. It is unlikely to cause as many problems as other two parts though.

Neither does acceptable job removing ads though. This stuff fails for cases where ads are not placed into specially named containers and served from the same server as valid content.

Turning off images leaves placeholders, sometimes occupying up to 2/3 of the page estate. In other words, turning off the images saves traffic but leaves page difficult to navigate.