Recommended server ram with large amount of contacts?

Hi we have about 50.000 contacts in Mautic now with about 5 campaigns running so we send a lot of emails every day. Everything works but we have notice that Mautic have become very slow nowadays. We are running the server on a digitalocean VPS that have about 1GB ram. How much ram is recommended for this amount of contacts?

Code:
free -m total used free shared buffers cached Mem: 1000 758 242 18 85 350 -/+ buffers/cache: 321 678 Swap: 634 275 359

Hi we have about 50.000 contacts in Mautic now with about 5 campaigns running so we send a lot of emails every day. Everything works but we have notice that Mautic have become very slow nowadays. We are running the server on a digitalocean VPS that have about 1GB ram. How much ram is recommended for this amount of contacts?

free -m total used free shared buffers cached Mem: 1000 758 242 18 85 350 -/+ buffers/cache: 321 678 Swap: 634 275 359

Thanks MxyzptlkFishStix,

But I now notice that the server is almost not usable when someone in our team are sending out email broadcasts.
Is there anyway to optimize this?