How would I reduce lag in duplication of blocks on roblox?

I’ve recently attempted to create an infinite mining sandbox game in Roblox very similar to "Mining Simulator," "Treasure Hunt Simulator,""Dig It!""Fish n’ Dig," and more. This particular problem has been preventing me from publishing the game.

When I have a pickaxe equipped, I start mining to lower depths and everything seems pretty normal. However, around depth 200-300, my game starts lagging excessively and the progress GUI bar at the bottom of my screen (the bar that lets me know how much progress there is left until the block I’m digging at is either broken or the value of the block lowers) starts lagging when I’m holding down the pickaxe. This obviously eventually makes the game unplayable.

I have a sufficiently high-end computer to run roblox.

The main cause of the lag seems to be from an excessive amount of minable blocks in the game that are cloned on all of the other minable blocks’ surfaces (besides the top) when a player mines it. I only see the lag improve when I manually delete some minable blocks from the Workspace which is obviously not a viable option since it would interfere with the main gameplay and purpose of the game. The minable blocks’ children do not consist of anything that would be a red-flag to lag, only string and number values to specify its durability, value, etc.