Using dplyr 1.1.0 and vctrs 0.5.2, I'm noticing speed issues when evaluating first within grouped tibbles.

df <- dplyr::group_by(tibble::tibble(x = 1:10000, grp = rep(1:100, 100)), grp)
bench::mark(
  first = dplyr::summarize(
    df,
    f = dplyr::first(x)
  ),
  indexed = dplyr::summarize(
    df,
    f = x[1]
  )
)
#> # A tibble: 2 x 6
#>   expression      min   median `itr/sec` mem_alloc `gc/sec`
#>   <bch:expr> <bch:tm> <bch:tm>     <dbl> <bch:byt>    <dbl>
#> 1 first        7.44ms   7.98ms      119.    1.57MB     19.1
#> 2 indexed      1.01ms   1.06ms      901.   55.62KB     12.7

On dplyr 1.0.10 with vctrs 0.5.0, the first benchmark is about 1.7 ms.