How to read Firestore data from my website without authentication? (Security required, Http Request takes too long)

I am building a website where some information from my Firestore database needs to be displayed. Currently I am using Cloud Functions with HTTP requests to load my data but because my function is not called very frequently the user experiences a "cold start" (up to 5 seconds) very often and even without a cold start the speed is not really satisfying (about 2 seconds). The data is only max. 200 Bytes so this should not be the problem.

Is there a better way or a common mistake which I might be doing? Are there any security concerns if my security rules would allow read-access without authentication for this collection?

Security is very important for this site and a certain document should be accessible depending on the URL. (https:URL/docID)