I've had great experience using an AWS Lightsail instance for over a year - $40/month 2CPU Windows package. I've recently moved to Kamatera for superfast connection, faster CPU, and more CPUs for less money -- 6CPUs 4GB RAM for $60/month.

Here is an important tips when using AWS Lightsail -- not sure about EC2.

The Zorro windows should be minimized to reduce CPU load. Since Lightsail are burstable instances with guaranteed baseline (like 10-20%). I find that when Zorro windows (I have several) are open at the same time, it uses more CPU. So I used cmdow in a scheduled task to minimize all my Zorros after they are up and running. This lowered my CPU utilization a great deal and when my Zorros come alive, it can burst up to 100% utilization for quite some time. Then overnight, you regain 4% of CPU burstability/per hour because nothing's going on.

In short, minimize ALL your windows (Zorro and others) when you don't need to interact with them.