Via the Steam store:

• Fixed a performance problem with some particles, including Tinker's March of the Machines, which would gradually degrade frame rate.
• Fixed a bug where creep and neutrals would spawn slightly later than expected in longer matches.

Rumor has it:

• A few protobuf tweaks, and a spacing tweak inside of profile pages with Greek/Turkish as the selected language: https://github.com/SteamDatabase/GameTracking/commit/3f030e10459ae9fd6430f9210053cdfecde7dcc1

• Size is ~80 MB - this size might be slightly higher if you have the workshop tools as those were updated as well