PBR and Specular Aliasing
I'll point out that even if you did implement it correctly, at 1 sample per pixel with low roughness materials you'll still see heavy specular aliasing. It's not uncommon to see the firefly pattern on edges on low roughness materials.
For reference see the Infiltrator demo without TAA

http://advances.realtimerendering.com/s2014/epic/TemporalAA_Compare.mov
http://advances.realtimerendering.com/s2014/index.html#_HIGH-QUALITY_TEMPORAL_SUPERSAMPLING