The Overclocker Upgrade promises a "Speed increase: 25%". However, that promise is wrong. It should instead display a "Time decrease: 25%".

Why
The code for the needed ticks is given by this formula.
this.currentNeededTicks = Math.max((int) (currentRecipe.getTime() * (1.0 - getSpeedMultiplier())), 1);
This means n Overclocker Upgrades do

• n=0: normal time (i.e. a 0% time decrease)
• n=1: 75% of normal time (i.e. a 25% time decrease)
• n=2: 50% of normal time (i.e. a 50% time decrease)
• n=3: 25% of normal time (i.e. a 75% time decrease)
• n=4: almost 0% of normal time (i.e. an almost 100% time decrease)

speed = unit/time, so modified speed = unit/(modified time) = unit/(factor * time) = 1/factor * unit/time = 1/factor * speed
("unit" being shorthand for "number of items smelted"). The factors are respectively 1, 0.75, 0.5, 0.25 and nearly 0, so n Overclocker Upgrades do

• n=0: normal speed (i.e. a 0% speed increase)
• n=1: 1.33 times normal speed (i.e. a 33% speed increase)
• n=2: doubled speed (i.e. a 100% speed increase)
• n=3: quadrupled speed (i.e. a 300% speed increase)
• n=4: instant smelting (1 tick) for vanilla metals which normally need 200 ticks means 200 times normal speed, (i.e. a 19,900% speed increase)

Environment

• Minecraft 1.17
• Fabric Loader 0.11.6
• Fabric API 0.36.0
• TR 5.0.3-beta+build.55

Without OC grinder produces 10 some dusts per minute.
With OC grinder produces 20 some dusts per minute.

Twice production speed increase ^_^

Yes, doubled speed. But not "Speed increase: 50%". That's my entire point.