I am experiencing an severe performance issue with Piper on my Windows system. After initialization, Piper runs extremely slowly for all languages I test (French, Malayalam, English), taking tens of seconds or minutes for very short phrases, or failing to produce output. This happens even for simple phrases like "Hello world."

Crucially, French and english were working correctly via a batch script previously, but now exhibits the same issue.

Observed Behavior:

Piper successfully loads the voice and initializes.

The console output shows Loaded voice and Initialized piper.

The process then takes an extremely long time (e.g., 11 seconds for "Hello world.", 24 seconds for "Bonjour le monde.", ~2 minutes for "നമസ്കാരം.").

During this prolonged processing time, Task Manager shows piper.exe's CPU usage is consistently very low (around 2%), indicating it's not effectively utilizing the CPU for computation. GPU usage is 0%.

For some longer texts, the process eventually terminates with [info] Terminated piper, but no .wav file is generated, or it is generated but the process is unacceptably slow. For others, it might appear to hang indefinitely until manually terminated.

My Environment:

Operating System: [Your exact Windows version, e.g., Windows 10 Home, version 22H2, OS build 19045.xxxx]

Piper Version:

Piper Directory: C:\piper trial1\piper_windows_amd64

Models Tested:

fr_FR-mls-medium.onnx

ml_IN-meera-medium.onnx

en_US-kristin-medium.onnx
..
C:\piper trial1\piper_windows_amd64>.\piper.exe --model ml_IN-meera-medium.onnx --output_file namaskaram_ml.wav --text "നമസ്കാരം."
[2025年07月01日 01:01:42.580] [piper] [info] Loaded voice in 0.309751 second(s)
[2025年07月01日 01:01:42.596] [piper] [info] Initialized piper
[2025年07月01日 01:02:00.832] [piper] [info^C
C:\piper trial1\piper_windows_amd64>
C:\piper trial1\piper_windows_amd64>.\piper.exe --model fr_FR-mls-medium.onnx --output_file bonjour_short.wav --text "Bonjour."
[2025年07月01日 01:02:03.027] [piper] [info] Loaded voice in 0.3078719 second(s)
[2025年07月01日 01:02:03.043] [piper] [info] Initialized piper
[2025年07月01日 01:03:35.358] [piper] [info] Terminated piper
^C
C:\piper trial1\piper_windows_amd64>
C:\piper trial1\piper_windows_amd64>chcp 65001
Active code page: 65001

C:\piper trial1\piper_windows_amd64>.\piper.exe --model fr_FR-mls-medium.onnx --output_file bonjour_short.wav --text "Bonjour."
[2025年07月01日 01:03:39.360] [piper] [info] Loaded voice in 0.3160231 second(s)
[2025年07月01日 01:03:39.375] [piper] [info] Initialized piper
[2025年07月01日 01:06:13.936] [piper] [info] Terminated piper
^C
C:\piper trial1\piper_windows_amd64>piper version

C:\piper trial1\piper_windows_amd64>.\piper.exe --model fr_FR-mls-medium.onnx --output_file bonjour_short.wav --text "Bonjour."
[2025年07月01日 01:08:17.179] [piper] [info] Loaded voice in 0.3102912 second(s)
[2025年07月01日 01:08:17.195] [piper] [info] Initialized piper
[2025年07月01日 01:09:37.974] [piper] [info^C
C:\piper trial1\piper_windows_amd64>

......

Troubleshooting Steps Already Performed:

Performed multiple fresh downloads and extractions of piper_windows_amd64.zip.

Ensured batch files are saved as UTF-8 and chcp 65001 is used at the start of the console/script.

Tried providing text directly (--text "...") and via temporary UTF-8 files (--text-file).

Moved the entire Piper installation to a new, simple path (C:\piper trial1).

Temporarily disabled antivirus/firewall and added the Piper directory to its exclusion list.

Ran Command Prompt as Administrator.

Checked Windows Event Viewer for application errors (no specific piper.exe errors found).

Tried in a minimal environment (after system reboot with no other apps running).

Confirmed espeak-ng-data/fr and espeak-ng-data/ml folders exist and appear to have content.

Critical: Observed consistently low CPU usage (around 2%) for piper.exe in Task Manager during the entire slow processing time.