User blog comment:SniperGhost/Garganus Sector Campaign/@comment-1187478-20110804100922/@comment-4206721-20110804172854

Tau vessels struggle to cross even interstellar distances and were so badly outclassed by the imperial navy in several notable campaigns navy commanders were executed for falsifying battle reports because subsector authorities couldn't believe the scale the naval officers claimed they were winning victories on. With forgeworlds introduction of an updated fleet for IA4 and the narrative around Taros, they've got some ground back, but they're still flimsy, low tech, slow, and undergunned compared with imperial counter parts. They have frontal firepower comparable to imperial ships broadsides (if slightly weaker in most cases) but, as I said, less tech and they are rubbish in boarding operations. (they use railguns, not lasers, ion cannons, not plasma lances, what they do have, they know how to use.)