Optimize skipNewlines scanning

[dduan]

Use local cursor/line counters in skipNewlines to reduce property writes, and tighten scanString loops by dropping redundant newline/dot checks during value and dotted-key scanning.

[github-actions]

Comparing results between 'main' and 'pull_request'

Host 'runnervmh13bl' with 4 'x86_64' processors with 15 GB memory, running:
#18~24.04.1-Ubuntu SMP Sat Jun 28 04:46:03 UTC 2025

TOMLDecoderBenchmarks

Decode toml.io example metrics

Time (wall clock): results within specified thresholds, fold down for details.

Time (wall clock) (μs) *	p0	p25	p50	p75	p90	p99	p100	Samples
main	70	71	71	72	77	91	150	6996
pull_request	70	71	71	73	81	99	141	6976
Δ	0	0	0	1	4	8	-9	-20
Improvement %	0	0	0	-1	-5	-9	6	-20

Retains: results within specified thresholds, fold down for details.

Retains *	p0	p25	p50	p75	p90	p99	p100	Samples
main	624	624	624	624	624	624	624	6996
pull_request	624	624	624	624	624	624	624	6976
Δ	0	0	0	0	0	0	0	-20
Improvement %	0	0	0	0	0	0	0	-20

Parse toml.io example metrics

Time (wall clock): results within specified thresholds, fold down for details.

Time (wall clock) (ns) *	p0	p25	p50	p75	p90	p99	p100	Samples
main	6562	6675	6715	6763	6855	10239	29244	10000
pull_request	6331	6495	6543	6615	6755	9735	34384	10000
Δ	-231	-180	-172	-148	-100	-504	5140	0
Improvement %	4	3	3	2	1	5	-18	0

Retains: results within specified thresholds, fold down for details.

Retains *	p0	p25	p50	p75	p90	p99	p100	Samples
main	8	9	9	9	9	9	9	10000
pull_request	8	9	9	9	9	9	9	10000
Δ	0	0	0	0	0	0	0	0
Improvement %	0	0	0	0	0	0	0	0

decode canada.toml metrics

Time (wall clock): results within specified thresholds, fold down for details.

Time (wall clock) (ms) *	p0	p25	p50	p75	p90	p99	p100	Samples
main	267	267	268	268	269	269	269	4
pull_request	267	267	267	267	268	268	268	4
Δ	0	0	-1	-1	-1	-1	-1	0
Improvement %	0	0	0	0	0	0	0	0

Retains: results within specified thresholds, fold down for details.

Retains (K) *	p0	p25	p50	p75	p90	p99	p100	Samples
main	1674	1674	1674	1674	1674	1674	1674	4
pull_request	1674	1674	1674	1674	1674	1674	1674	4
Δ	0	0	0	0	0	0	0	0
Improvement %	0	0	0	0	0	0	0	0

decode twitter.toml metrics

Time (wall clock): results within specified thresholds, fold down for details.

Time (wall clock) (μs) *	p0	p25	p50	p75	p90	p99	p100	Samples
main	9396	9470	9544	9626	9683	9986	10198	104
pull_request	9352	9413	9454	9527	9765	10527	10848	104
Δ	-44	-57	-90	-99	82	541	650	0
Improvement %	0	1	1	1	-1	-5	-6	0

Retains: results within specified thresholds, fold down for details.

Retains (K) *	p0	p25	p50	p75	p90	p99	p100	Samples
main	66	66	66	66	66	66	66	104
pull_request	66	66	66	66	66	66	66	104
Δ	0	0	0	0	0	0	0	0
Improvement %	0	0	0	0	0	0	0	0

parse canada.toml metrics

Time (wall clock): results within specified thresholds, fold down for details.

Time (wall clock) (ms) *	p0	p25	p50	p75	p90	p99	p100	Samples
main	17	18	18	19	19	37	37	53
pull_request	17	18	18	18	19	20	20	55
Δ	0	0	0	-1	0	-17	-17	2
Improvement %	0	0	0	5	0	46	46	2

Retains: results within specified thresholds, fold down for details.

Retains *	p0	p25	p50	p75	p90	p99	p100	Samples
main	132	133	133	133	133	133	133	53
pull_request	132	133	133	133	133	133	133	55
Δ	0	0	0	0	0	0	0	2
Improvement %	0	0	0	0	0	0	0	2

parse twitter.toml metrics

Time (wall clock): results within specified thresholds, fold down for details.

Time (wall clock) (μs) *	p0	p25	p50	p75	p90	p99	p100	Samples
main	3035	3092	3111	3148	3215	3572	4029	313
pull_request	3093	3129	3144	3162	3181	3394	3643	312
Δ	58	37	33	14	-34	-178	-386	-1
Improvement %	-2	-1	-1	0	1	5	10	-1

Retains: results within specified thresholds, fold down for details.

Retains *	p0	p25	p50	p75	p90	p99	p100	Samples
main	1292	1293	1293	1293	1293	1293	1293	313
pull_request	1292	1293	1293	1293	1293	1293	1293	312
Δ	0	0	0	0	0	0	0	-1
Improvement %	0	0	0	0	0	0	0	-1