Enchanting tables have a relatively low (although still present) impact on TPS, but the animation of the book spinning closed when distant, opening and tracking the player when nearby, has enough impact on the client FPS, that clients that don't disable it (through a hack), in presence of a massive amount of enchanting tables can drop framerate to unplayable levels and even crash.

Even more massive numbers of the tables - measured in multiple chunks of volume - will accumulate server lag from tile ticking to a degree that can lag the server, although there are more efficient ways to achieve that.

FitMC describes the abuse of enchanting tables for this purpose in his video "How Mr. Beast Destroyed Minecraft's 2b2t" at 6:14

Enchanting tables have a relatively low (although still present) impact on TPS, but the animation of the book spinning closed when distant, opening and tracking the player when nearby, has enough impact on the client FPS, that clients that don't disable it (through a hack), in presence of a massive amount of enchanting tables can drop framerate to unplayable levels and even crash.

Even more massive numbers of the tables - measured in multiple chunks of volume - will accumulate server lag from tile ticking to a degree that can lag the server, although there are more efficient ways to achieve that.

Probably in your case the cube simply wasn't big enough for that.

FitMC describes the abuse of enchanting tables for this purpose in his video "How Mr. Beast Destroyed Minecraft's 2b2t" at 6:14