full configs are available on github (and more updated).
There are also a lot of other companies/packages to help you setup faster stacks that are more maintained than what I did. easyEngine or ServerPilot being two examples.
How many hits are you getting per day that isn't great performance? I'm running two WP blogs each on their own $5/mo plan and it's been working great with one notable exception: I would constantly run out of memory on my highest-trafficked site (20 uniques per day) with WP Super Cache turned on. When I uninstalled it, the speed went way up and the out of memory errors disappeared.
https://github.com/kevinohashi/WordPressVPS you can take a look at the loadtest_results folder to see. I tested a lot of different configurations and plugins. The default LAMP stack which DO provides starts to struggle at 10 users. While some configs were doing fine over 1000.
full configs are available on github (and more updated).
There are also a lot of other companies/packages to help you setup faster stacks that are more maintained than what I did. easyEngine or ServerPilot being two examples.