New subject: [Bug 59514] time()/localtime() performance has regressed significantly

March 12, 2026

      http://bugs.winehq.org/show_bug.cgi?id=59514

            Bug ID: 59514
           Summary: Significant time()/localtime() Performance Regression
                    in Wine 11.4
           Product: Wine
           Version: 11.4
          Hardware: x86-64
                OS: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: ucrtbase
          Assignee: wine-bugs@list.winehq.org
          Reporter: wszqkzqk@qq.com
      Distribution: ---

Created attachment 80538
  --> http://bugs.winehq.org/attachment.cgi?id=80538
Minimal reproducer: time() / localtime() performance regression in Wine 11.4

Repeated calls to `time()` and `localtime()` are significantly slower in Wine
11.4 compared to Wine 11.3.
A tight loop calling these functions 10000 times shows a clear regression in
per-call cost.
The same program compiled and run natively on Linux is orders of magnitude
faster, confirming the overhead is in Wine's translation layer.

Compared with Wine 11.3, per-call cost increases from about 12.8 us to about
319 us, roughly a **25x slowdown**.

## Environment

- Host OS: Arch Linux, Latest
- CPU: AMD Ryzen 5800H (laptop without power)
- Wine versions tested: 11.3 / 11.4

## Minimal Reproducer

Single-file C program. See in the attachment.

Build as a Windows PE executable (e.g. using a Windows-native gcc under Wine):

```bash
wine gcc -O2 -o time_bench.exe time_bench.c
```

Build as a native Linux executable for baseline comparison:

```bash
gcc -O2 -o time_bench time_bench.c
```

Run:

```bash
# Wine
wine ./time_bench.exe

# Native Linux baseline
./time_bench
```

## Reproduction Steps

1. Compile `time_bench.exe` as a Windows PE executable.
2. Compile `time_bench` as a native Linux executable on the same machine.
3. Run the PE binary under Wine 11.3 — record the output.
4. Run the same PE binary under Wine 11.4 — record the output.
5. Run the native Linux binary — record the output as baseline.
6. Compare the `ns/call` values.

## Expected Result

Per-call cost of `time()` and `localtime()` should be roughly the same between
Wine 11.3 and Wine 11.4.

## Actual Result

Wine 11.4 shows a significant increase in per-call cost.

### Wine 11.3

```text
iterations: 10000

time()      : 0.128437 s  (12844 ns/call)
localtime() : 0.129727 s  (12973 ns/call)

sink=17732949360000
```

### Wine 11.4

```text
iterations: 10000

time()      : 3.196547 s  (319655 ns/call)
localtime() : 3.184343 s  (318434 ns/call)

sink=17732948683316
```

### Native Linux (baseline)

```text
iterations: 10000

time()      : 0.000103 s  (10 ns/call)
localtime() : 0.058464 s  (5846 ns/call)

sink=17732948500000
```

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[Bug 59514] New: Significant time()/localtime() Performance Regression in Wine 11.4

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