x265 can achieve the same visual quality as x264 while using up to 50% less disk space . This means a 1080p episode that might take up 1GB in x264 could be reduced to ~500MB in x265 with no discernible loss in quality.
Looking back at Season 1, it is striking how quickly the show found its voice. In "Pilot," we aren't eased into the world; we are immediately hit with the catchphrase ("Wubba Lubba Dub Dub!") and the nihilistic philosophy that defines Rick Sanchez.
For the uninitiated, x265 (HEVC) is the gold standard for modern digital hoarders. It allows a high-definition file to be compressed to a fraction of the size of its x264 predecessor.
Animation often contains large areas of flat, solid colors. The x265 codec uses Coding Tree Units (CTUs) up to 64x64 pixels, which are much more efficient at "grouping" these uniform areas than the smaller 16x16 macroblocks used in x264.
In "Lawnmower Dog," we see the inception logic that would later define the show's smartest episodes. In "Close Rick-counters of the Rick Kind," we get our first glimpse of the Citadel, a concept that would eventually consume the series. Having these episodes in a portable, lightweight format is like having a pocket bible for the church of nihilism.