We pick up the default GTK dpi settings, and if that's not suitable, you can use the dpi_scale setting to set it specifically (you'll have to restart Sublime Me

We pick up the default GTK dpi settings, and if that's not suitable, you can use the dpi_scale setting to set it specifically (you'll have to restart Sublime Merge after changing it though). I run Sublime Merge on high dpi screen under Linux every day FWIW.