https://victoriametrics.com/ would definitely recommend anyone having performance issues with Prometheus to give VictoriaMetrics a try.
Here’s an article about this idea: https://datadrivendrivel.com/posts/rmrfprometheus/
You can substitute the Grafana Agents for OTEL collectors as well.
P.S. Prometheus itself can also act as a lightweight agent, which collects metrics and forwards them to the configured remote storage [2].