Franz launches a completely new instance for every workspace/network that you add and these are based on their regular webviews. Unlike Slack, it will not unload less frequently used workspaces from your RAM and with 8 Slack workspaces, Telegram, Whatsapp and IRCCloud it managed to permanently allocate more than 3 GiB RAM. That may be fine on my beefy desktop PC but not on my MacBook Air with only 8 GiB RAM.

In my case, just leaving the official apps of these chat networks in the background seems to be less resource intensive than running Franz. I really hope that https://eul.im/ will up to my expectations.