Libh2o (the protocol implementation) support both libuv and evloop (our tailor-made event loop).
The default event loop of libh2o is libuv, since libuv is popular and has bindings to other protocols (which you would need if you want to implement an application using libh2o).
OTOH the standalone server uses evloop for performance.
The default event loop of libh2o is libuv, since libuv is popular and has bindings to other protocols (which you would need if you want to implement an application using libh2o).
OTOH the standalone server uses evloop for performance.