This library uses a PCF8575 to read the pulses of a rotary encoder. As a PCF8575 has 16 lines up to 5 decoders with a switch can be read over I2C ... Early tests gave the following indicative times ...

This Arduino library decodes bidirectional toggle switches (e.g., ALPS SSCM110100) as rotary encoders. It tracks switch toggling triggered by gears or mechanical rotation, determining clockwise (CW) ...