IMPORTANT. This issue focuses on gas cost for the execution of the user, as measured here:

https://github.com/RareSkills/RSA-presale-allowlist/blob/main/test/rsa.test.js#L182

Although we welcome suggestions to improve the other gas costs, this is the one relevant to the gitcoin bounty.

"Clever but sketchy" gas optimizations don't qualify. This is intended to be used for production. You may not introduce security or reliability vulnerabilities. Restructuring the code to accomplish the same thing in a better way is acceptable. You are not required to follow the current structure of the code.

Bounty sponsored by RareSkills