RWLock is important?

[stokito]

The GetCertificate uses a RWLock

func (cm *CertMan) GetCertificate(hello *tls.ClientHelloInfo) (*tls.Certificate, error) {
	cm.mu.RLock()
	defer cm.mu.RUnlock()

	return cm.keyPair, nil
}

Is the lock is really needed? There is really no concurrent modifications. But the lock makes performance slower.