Multiply note lengths in UST files. Works for both UTAU and UTAU-Synth. Optionally, multiply the tempo as well, so that the apparent speed is the same as the original UST.
Download and run MultiplyNoteLength.jar to run. Make sure the UST you want to multiply is in the same folder as the jar. You can enter the file name without ".ust" at the end, but it can't have any spaces. If the UST is in Shift-JIS, the result will turn out blank if the UST contains Japanese characters. Otherwise, lyrics should stay intact.