i2cdisplaybus + 10.0.3 is twice slower than 9.2.9

[mrbbp]

CircuitPython version and board name

Adafruit CircuitPython 10.0.3 on 2025-10-17; Seeeduino XIAO RP2040 with rp2040
Board ID:seeeduino_xiao_rp2040

and

Adafruit CircuitPython 9.2.9 on 2025-09-07; Seeeduino XIAO RP2040 with rp2040
Board ID:seeeduino_xiao_rp2040

Code/REPL

displayio.release_displays()
i2c = busio.I2C(board.D5, board.D4)
# CircuitPython 10: Utilisation de i2cdisplaybus pour créer le bus I2C
display_bus = i2cdisplaybus.I2CDisplayBus(i2c, device_address=0x3C)
# adafruit_displayio_ssd1306
display = adafruit_displayio_ssd1306.SSD1306(display_bus, width=SCREEN_WIDTH, height=SCREEN_HEIGHT)

[...] 
    # Temps après la création de l'image, avant l'affichage
    before_refresh_time = time.monotonic()
    
    # Mettre à jour l'écran
    display.refresh()
    
    # Temps après l'affichage
    after_refresh_time = time.monotonic()
    
    # Calculer les durées
    creation_time = (before_refresh_time - start_time) * 1000  # en millisecondes
    refresh_time = (after_refresh_time - before_refresh_time) * 1000  # en millisecondes
    total_time = (after_refresh_time - start_time) * 1000  # en millisecondes
    
    # Afficher les statistiques toutes les 10 frames pour ne pas saturer le terminal
    if frame_in_phase_counter % 10 == 0:
        print(f"Timings - Création: {creation_time:.2f}ms | Refresh: {refresh_time:.2f}ms | Total: {total_time:.2f}ms")

Behavior

Adafruit CircuitPython 9.2.9 on 2025-09-07; Seeeduino XIAO RP2040 with rp2040
Board ID:seeeduino_xiao_rp2040
UID:4250305031363910

Écran SSD1306 et LDR initialisés.
Démarrage de l'animation rapide avec division aléatoire.
Timings - Création: 14.16ms | Refresh: 73.00ms | Total: 87.16ms
Timings - Création: 14.16ms | Refresh: 73.97ms | Total: 88.13ms
Timings - Création: 13.92ms | Refresh: 73.00ms | Total: 86.91ms
Timings - Création: 14.16ms | Refresh: 73.00ms | Total: 87.16ms
Timings - Création: 13.92ms | Refresh: 73.97ms | Total: 87.89ms
Timings - Création: 14.16ms | Refresh: 73.97ms | Total: 88.13ms
Timings - Création: 12.94ms | Refresh: 73.00ms | Total: 85.94ms
Timings - Création: 14.89ms | Refresh: 73.00ms | Total: 87.89ms
Timings - Création: 15.87ms | Refresh: 73.00ms | Total: 88.87ms
Timings - Création: 13.92ms | Refresh: 73.00ms | Total: 86.91ms
Timings - Création: 18.07ms | Refresh: 71.04ms | Total: 89.11ms
Timings - Création: 18.07ms | Refresh: 73.97ms | Total: 92.04ms
Timings - Création: 18.07ms | Refresh: 71.04ms | Total: 89.11ms
Timings - Création: 18.07ms | Refresh: 73.00ms | Total: 91.06ms
Timings - Création: 19.04ms | Refresh: 71.04ms | Total: 90.09ms
Timings - Création: 17.82ms | Refresh: 70.07ms | Total: 87.89ms
Timings - Création: 18.80ms | Refresh: 70.07ms | Total: 88.87ms
Timings - Création: 18.07ms | Refresh: 72.02ms | Total: 90.09ms
Timings - Création: 18.07ms | Refresh: 70.80ms | Total: 88.87ms
Timings - Création: 18.07ms | Refresh: 73.00ms | Total: 91.06ms
Timings - Création: 16.11ms | Refresh: 71.78ms | Total: 87.89ms
Timings - Création: 13.92ms | Refresh: 73.00ms | Total: 86.91ms
Timings - Création: 12.94ms | Refresh: 73.00ms | Total: 85.94ms

Adafruit CircuitPython 10.0.3 on 2025-10-17; Seeeduino XIAO RP2040 with rp2040
Board ID:seeeduino_xiao_rp2040
UID:4250305031363910

Écran SSD1306 et LDR initialisés.
Démarrage de l'animation rapide avec division aléatoire.
Timings - Création: 13.00ms | Refresh: 149.02ms | Total: 162.02ms
Timings - Création: 13.98ms | Refresh: 147.00ms | Total: 160.98ms
Timings - Création: 13.00ms | Refresh: 139.98ms | Total: 152.98ms
Timings - Création: 13.00ms | Refresh: 140.01ms | Total: 153.02ms
Timings - Création: 13.00ms | Refresh: 139.01ms | Total: 152.01ms
Timings - Création: 14.01ms | Refresh: 145.02ms | Total: 159.03ms
Timings - Création: 13.00ms | Refresh: 138.00ms | Total: 151.00ms
Timings - Création: 14.01ms | Refresh: 143.01ms | Total: 157.01ms
Timings - Création: 11.99ms | Refresh: 142.00ms | Total: 153.99ms
Timings - Création: 14.01ms | Refresh: 144.99ms | Total: 159.00ms
Timings - Création: 13.98ms | Refresh: 144.01ms | Total: 157.99ms
Timings - Création: 14.01ms | Refresh: 143.98ms | Total: 157.99ms
Timings - Création: 14.01ms | Refresh: 143.98ms | Total: 157.99ms
Timings - Création: 14.01ms | Refresh: 142.97ms | Total: 156.98ms
Timings - Création: 13.00ms | Refresh: 143.01ms | Total: 156.01ms
Timings - Création: 15.99ms | Refresh: 148.01ms | Total: 164.00ms
Timings - Création: 17.00ms | Refresh: 142.00ms | Total: 159.00ms
Timings - Création: 14.98ms | Refresh: 144.01ms | Total: 159.00ms
Timings - Création: 13.00ms | Refresh: 146.00ms | Total: 159.00ms
Timings - Création: 13.00ms | Refresh: 142.00ms | Total: 155.00ms
Timings - Création: 13.00ms | Refresh: 146.00ms | Total: 159.00ms
Timings - Création: 13.00ms | Refresh: 144.01ms | Total: 157.01ms
Timings - Création: 13.00ms | Refresh: 145.02ms | Total: 158.02ms
Timings - Création: 13.00ms | Refresh: 144.99ms | Total: 157.99ms
Timings - Création: 13.00ms | Refresh: 147.00ms | Total: 160.00ms
Timings - Création: 13.00ms | Refresh: 145.02ms | Total: 158.02ms
Timings - Création: 11.99ms | Refresh: 144.01ms | Total: 156.01ms
Timings - Création: 11.99ms | Refresh: 148.99ms | Total: 160.98ms
Timings - Création: 13.00ms | Refresh: 148.01ms | Total: 161.01

Description

same code for the same model board and same model oled display.
one is with CP9.2.9 the other with CP10.0.3

Additional information

No response

[bablokb]

This might be related to #10733

[dhalbert]

I see the same timing issue with a similar test program that sets up an I2C display and then changes the text and color. It's twice as slow starting with 10.0.0-alpha.3. 10.0.0-alpha.2 is similar to 9.2.9.

If I simply write a for _ in range(10000): pass style loop, I do not see a slowdown.

I believe the slowdown is due to #10277. Whether the additional background tasks are due to SD card support, I'll see. EDIT: still slow when I turn off SD card support. WIll investigate further.