DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.
Plugin commands, skills, and agents are now loaded using Promise.all for concurrent processing, improving startup time when multiple plugins are installed. Previously, plugins were loaded sequentially in for loops.
Evidence
Parallel loading (search for "Promise.all" in the plugin loading functions)
Strings lifted out of the shipped bundle, so the claim above can be checked against them.
Related
Other releases about the same thing. Found by shared names or similar wording; neither means one caused the other.