Bessemer Venture Partners have written a guide with 40 areas software companies can address to increase gross profit and efficiency. It covers a bunch of areas and is a good checklist, even if there is no groundbreaking ideas (which would be surprising when you are looking to increase efficiency).
One interesting data point is their benchmark for payback time for customer acquisition costs for SaaS. Payback time can be longer for larger customers, not surprising as it often takes longer to acquire them, but should be below 12 months to be great for all types of customers.
(source: Bessemer Venture Partners)
Two other data points are that public cloud companies spend 20 % of revenue on R&D (mainly engineering) and 12 % on G&A (everything that is not sales & marketing or research & development). Those are numbers to aim for and try to beat as a SaaS company grows.