Mark Smith has a nice write-up on optimizing the 5v to 170v Nixie tube power supply:
Since this power supply is just a fun design for an upcoming Nixie tube clock project of mine, I have the time to achieve ESE. While in Part 1 I described the equations and simulations, in this Part 2, I collected experimental results to complete the design. In the process of finalizing the design, I was able to discover a couple of key design improvements and I’ll share these changes with you. The updated schematic, BOM, Kicad Layout, and design files are located at Github.