Hey folks,
I've been deep in the SAST vs. IAST weeds lately, specifically with Checkmarx's offerings. We've standardized on CxSAST for pre-merge scans in our CI/CD (FastAPI apps, Dockerized), but the promise of runtime analysis with CxIAST is really appealing for catching things SAST can't.
My question is about raw performance. SAST scans can be... a journey, especially on a large monolith before we broke it up. IAST is supposed to be "always on" during tests, but I'm trying to wrap my head around the actual time cost.
Has anyone done a side-by-side benchmark or have real-world numbers on scan/analysis times? I'm curious about:
* **CxSAST:** Full scan duration vs. incremental/diff scan times on a typical microservice.
* **CxIAST:** The overhead it adds to your automated test suite runtime (like a pytest session). Does it slow down the tests themselves noticeably?
For context, our typical SAST scan on a medium service looks like this in the pipeline:
```yaml
- name: Run CxSAST Scan
run: |
# This is a simplified wrapper call
python run_cx_scan.py --project-id ${PROJECT_ID} --incremental
```
The full scan can take 12-15 minutes, but incrementals are under 3. If IAST adds, say, 30% to my 5-minute integration test run, that's a very different trade-off than if it doubles it.
I'm especially interested in the integration point. Does the IAST agent play nicely with Python/ASGI, or is there a lot of config tuning to get it efficient?
Love to hear any war stories or hard numbers you've collected.
~d
Those incremental CxSAST times are about what we saw, too. The real cost creep isn't the pipeline minutes, it's the engineer-hours waiting for the full scan gate to pass. That's where the math gets interesting.
For IAST overhead, think of it as adding latency, not duration. Each test call gets instrumented, so the slowdown is per-transaction. On a test suite with thousands of fast, simple API calls, we saw a 30-40% increase in total runtime. For a suite of a few dozen complex integration tests, it was more like 10-15%.
Have you factored in the IAST agent's resource consumption on your test runners? That's where another hidden tax shows up.
Cloud costs are not destiny.
Interesting numbers on the IAST overhead. That 30-40% hit on a large test suite is a lot.
Quick follow-up, since you mentioned the agent's resource tax: what kind of memory footprint are we talking about on the test runners? Our CI containers are already pretty lean.