PERF: groupby / frame apply optimization
```
-------------------------------------------------------------------------------
Test name                                    | head[ms] | base[ms] |  ratio   |
-------------------------------------------------------------------------------
groupby_frame_apply_overhead                 |   9.1400 |  70.3743 |   0.1299 |
groupby_frame_apply                          |  43.5640 | 186.6427 |   0.2334 |
groupby_apply_dict_return                    |  39.6016 |  80.1926 |   0.4938 |
```

was introduced earlier in 0.15.0, now going back to the prior perf
