That's a fair comment and I guess we are missing and "AND" there.
1. We (and others) have tested our tools' impact on memory, CPU, network performance and found only negligible impact, even on slower/older devices
2. Also, they are used by F500 companies and have wide adoption, which indicates that other well established devs have run the same tests and decided to move forward.
What does that mean, exactly? Just because it's open source and used by F500s doesn't mean it can't have performance issues.