Forum posting is also a way to create backlinks but you should use it in the right way. If you use forum sites for your website promotion and create unnecessary links then this will go into spam, and your account will be terminated by the moderators.
How much work do you really do? If you have seen results you keep working it. Link building is the strongest way of achieving traffic but must be reciprocated. No point sending off all your clicks for no return. I assume your writing the content.
Spamming forums with promotional posts will get you banned and the links you get from it will be worthless even if the moderators don't remove your posts. As with everything else, there is a wrong and right way to go about getting links from forums.