If it chugs that badly with one user and zero load, I'm gonna assume it'll tip over if I so much as look at it funny.
SaaS is not the website itself. It's paying for risk management. For example, why did you use AWS instead of the wayyyy cheaper server-under-a-desk? At your scale, I bet it would be more than adequate.
If _you_ don't want to self-host something core to your business, think about why. Congrats, you now understand why people pay for SaaS.