I second kawecki - Meshlab does very good decimations. It has never crashed on me, but there is always a first time...

Poser 11 Pro, Windows 10

Auxiliary Apps: Blender 2.79, Vue Complete 2016, Genetica 4 Pro, Gliftex 11 Pro, CorelDraw Suite X6, Comic Life 2, Project Dogwaffle Howler 8, Stitch Witch