DS (5) was similar at that age, still is with unknown children. This..
"When presented with new activities, even one-on-one with me, he prefers to see the process from start to finish before actively engaging. Then, once his understanding of the activity or concept is well formed, he dives in confidently and enthusiastically and performs effectively flawlessly"
...was perfectionism related for DS.
Socially at that age our best bet was one in one with selected children, preferably ones with older siblings, adults, adolescents and some formal groups. Grade 1 now and like a different child socially at school (very comfortable), compared with being at the park with unknown children.
It's a tricky age when your peer group can't really talk/understand you...
