LoadAndRender

// SPDX-License: BEER
pragma solidity ^0.8.0;

contract MyBigNFTStorage {

  mapping(uint256 => string) public _SVGChunks;
  uint256 ChunkCount;

  // Limited to 25kb
  function loadSVGChunk(uint256 id, string memory chunk) public {
    // Will store inside storage a chunk with ID
    _SVGChunks[id] = chunk;
    if (id > ChunkCount) {
      ChunkCount = id;
    }
  }

  function render(/* arguments for seach& replace goes here*/) public view returns (string memory output) {
    string memory buffer;
    for (uint256 i = 0; i <= ChunkCount; i++) {
      buffer = string(abi.encodePacked(buffer, _SVGChunks[i]));
    }
    // Search & Replace in-memory for parameters
    // - rate
    return buffer;
  }
}