Required:
Items & Blocks.
Building A Structure In Depth.
Structure Script Block.
Dynamic Structures.

The one limitation of Recurrent Complex is structure size. Very large structures can cause lag or even temporary freezes. One method to alleviate this without compromising on structure size is to segment your structure into parts that will generate from structure script blocks based on player proximity. For this to work, you'll need to either use pressure plates (least effective), or proximity triggered redstone sources (there are various mods for this, but my preferred one is CustomNPC). The parent structure will generate with a smaller portion of the structure which includes the entrance, and when players get close to it, the second portion of the structure generates (you can chain these as many times as you want). For this to work without looking weird, it is almost exclusively restricted to underground structures unless you set a very large proximity trigger radius on the redstone trigger block. This method essentially spreads the generation of your structure out over multiple game ticks to reduce CPU load. To ensure that the script block only triggers once, you'll need to have a command block connected that will use a relative position fill command to delete the command block, script block, and redstone trigger block once it activates.

Drawbacks:

This method does have several drawbacks you should be aware of. If the sectioned pieces of your structure are larger than the trigger radius, there is a chance player's bases may get overwritten if they build nearby.

The CNPC redstone trigger block also makes it impossible to edit the structure once placed as it will trigger when you get close. To allow editing the structure later, you'll need to create a dummy quest ahead of time and set the rules of the redstone block to only trigger when the player doesn't have that quest active (something like Dummy Edit Quest). Then you can just give yourself that quest through an NPC and approach your structure without worry. Note that the redstone block will also trigger as soon as it's placed down since you're within range when doing so, and only turns off after you've exited the GUI. This means you'll need to place it at least one block away from the command and script blocks and then connect them afterwards with redstone, or place it before you place the command blocks.