Frames manager is plugin to manage Game frames it supports managing Average Frames and Target Frames till now,
you can limit your frames or you can increase Max Frames to see performance of your GPU for instance.
There is support for In-Game FPS also it measures your Frames only when you are in game.
And it supports multiple UI to show frames you can press F5 for Frames manager and F6 for Frames Text UI option anytime.
It has very customizable UI you can go to settings and change UI window position, Text color/font etc.
ImGui - Main floating window UI for Frames Manager.