Please try the solution in the FAQ Texts in the furniture catalog are not displayed correctly or icons in the toolbar appear very small on my computer. How can I fix that?
As you're a developer and Java 9 is supposed to fix this issue, it would be nice if you could also try to install Java 9 on your computer and run Sweet Home 3D with it, either with Java Web Start or with the JAR Executable version (About dialog box will confirm which Java version is used). I don't have any HiDPI PC running under Windows and wonder how it works...