Sorry to hear you're having troubles.

You can find a list of optimization recommendations here on the spine-unity documentation page:
spine-unity Runtime Documentation: Performance
Erika also recently posted a very good list here on the forum:
Optimize spine file

Your profiler screenshot shows that clipping is taking a lot of time in your scene at runtime (in every frame, not at loading time). In general please always consider avoid using clipping polygons (if possible), and consider using Unity's masking features instead (components like Mask, RectMask2D, SpriteMask). Please note that whenever profiling with deep profile mode enabled, timings can be distorted very much, so be sure to check with deep profile disabled as well to get more realistic time stamps.

The most important recommendation regarding loading times is to use binary (.skel.bytes) export instead of .json, as listed in the sources above.