Well, following your example, since split dicts seems to be no more supported, I decided to be more drastic. If you see the last push in PR 22346, I do not check anymore but always resize, so the dict is always combined. This seems to be especially good for the "unpack_sequence" bench, even if I do not know what it is:

| chaos                   | 132 ms           | 136 ms         | 1.03x slower | Significant (t=-18.09) |
| crypto_pyaes            | 136 ms           | 141 ms         | 1.03x slower | Significant (t=-11.60) |
| float                   | 133 ms           | 137 ms         | 1.03x slower | Significant (t=-16.94) |
| go                      | 276 ms           | 282 ms         | 1.02x slower | Significant (t=-11.58) |
| logging_format          | 12.3 us          | 12.6 us        | 1.02x slower | Significant (t=-9.75)  |
| logging_silent          | 194 ns           | 203 ns         | 1.05x slower | Significant (t=-9.00)  |
| logging_simple          | 11.3 us          | 11.6 us        | 1.02x slower | Significant (t=-12.56) |
| mako                    | 16.5 ms          | 17.4 ms        | 1.05x slower | Significant (t=-17.34) |
| meteor_contest          | 116 ms           | 120 ms         | 1.04x slower | Significant (t=-25.59) |
| nbody                   | 158 ms           | 166 ms         | 1.05x slower | Significant (t=-12.73) |
| nqueens                 | 107 ms           | 111 ms         | 1.03x slower | Significant (t=-11.39) |
| pickle_pure_python      | 631 us           | 619 us         | 1.02x faster | Significant (t=6.28)   |
| regex_compile           | 206 ms           | 214 ms         | 1.04x slower | Significant (t=-24.24) |
| regex_v8                | 28.4 ms          | 26.7 ms        | 1.06x faster | Significant (t=10.92)  |
| richards                | 87.8 ms          | 90.3 ms        | 1.03x slower | Significant (t=-10.91) |
| scimark_lu              | 165 ms           | 162 ms         | 1.02x faster | Significant (t=4.55)   |
| scimark_sor             | 210 ms           | 215 ms         | 1.02x slower | Significant (t=-10.14) |
| scimark_sparse_mat_mult | 6.45 ms          | 6.64 ms        | 1.03x slower | Significant (t=-6.66)  |
| spectral_norm           | 158 ms           | 171 ms         | 1.08x slower | Significant (t=-29.11) |
| sympy_expand            | 599 ms           | 619 ms         | 1.03x slower | Significant (t=-21.93) |
| sympy_str               | 376 ms           | 389 ms         | 1.04x slower | Significant (t=-23.80) |
| sympy_sum               | 233 ms           | 239 ms         | 1.02x slower | Significant (t=-14.70) |
| telco                   | 7.40 ms          | 7.61 ms        | 1.03x slower | Significant (t=-10.08) |
| unpack_sequence         | 70.0 ns          | 56.1 ns        | 1.25x faster | Significant (t=10.62)  |
| xml_etree_generate      | 108 ms           | 106 ms         | 1.02x faster | Significant (t=5.52)   |
| xml_etree_iterparse     | 133 ms           | 130 ms         | 1.02x faster | Significant (t=11.33)  |
| xml_etree_parse         | 208 ms           | 204 ms         | 1.02x faster | Significant (t=9.19)   |