Configurable Mining Delay
This is a fully client-side mod that allows you to change the delay between mining and placing blocks.
The mining delay can be changed from the default 5 ticks to 0-20, using the command /miningdelay delay <ticks>, and the placement delay can be changed from the default 4 ticks to 0-20, using the command /miningdelay placement_delay <ticks>.
By default, delay modification is disabled when connected to a server, as most servers with anti-cheat enabled will ban you for doing it. Using the command /miningdelay enabledOnServers true will enable the modified mining delay on servers, and /miningdelay enabledOnServers false will disable it again.
Changes you make via commands are saved to miningdelay.json located in the config folder. Note that manually editing the file while in-game won't apply the changes in real-time like the commands do.
