How do you integrate Semgrep into CI/CD without slowing delivery to a crawl?

The usual failure mode is a security gate so slow or noisy that teams bypass it. For Semgrep, the practical levers are: scan only what changed on pull requests and keep the exhaustive scan for a nightly or pre-release run; cache whatever database or ruleset the tool downloads so CI is not re-fetching it every job; and parallelise across services rather than scanning a monorepo serially.

Severity policy matters as much as speed. Blocking on every finding trains people to add blanket suppressions. A workable policy blocks on Critical (and often High) with a documented, time-boxed exception process, while everything lower is tracked as a ticket rather than a hard stop.

For this tool specifically, tune writing and tuning custom rules, pattern syntax vs regex, per-language rulesets, autofix, baseline scanning on diffs only, false-positive suppression with nosemgrep, and running as a fast pre-commit and CI gate. Finally, make the gate honest: blocking a merge when a rule matches on changed lines. A gate that warns but never blocks is documentation, not a control.