I'm unhappy with Synapse because of performance and admin overhead; what should I use instead?

If you mean Matrix Synapse, the usual alternatives depend on what you’re trying to optimize for:

Best general alternative: Dendrite

• Official Matrix homeserver from the Matrix team
• Designed to be lighter and more scalable than Synapse
• Good if you want to stay in the Matrix ecosystem but reduce overhead
• Tradeoff: it’s still maturing, and some features/admin workflows may not be as polished as Synapse

If you want a simpler, faster chat stack: Zulip

• Excellent for team communication
• Much easier to run than Synapse for many orgs
• Strong search, threading, and moderation/admin tools
• Tradeoff: it’s not federated like Matrix and has a different chat model

If you want real-time chat with low ops burden: Rocket.Chat or Mattermost

• Both are easier to operate than a Matrix stack for many deployments
• Good for internal org chat, integrations, channels, and admin control
• Tradeoff: not decentralized/federated in the Matrix sense

If your priority is federation + performance, but not necessarily Matrix compatibility:

• XMPP with Prosody or ejabberd
  • Much lighter operationally
  • Mature federation
  • Tradeoff: ecosystem and UX can feel less modern than Matrix

Practical recommendation

• Stay in Matrix but improve performance/admin overhead: try Dendrite
• Need easiest self-hosted team chat: consider Zulip
• Need Slack-like internal chat with lower ops: Mattermost or Rocket.Chat
• Need federated messaging but want less complexity: XMPP

If you tell me:

1. how many users you have,
2. whether federation is required,
3. whether this is for internal chat or public/community chat,

…I can recommend the best fit more precisely.