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Fixed in 5.6.0f3

Won't Fix in 5.3.X

Fixed in 5.4.X, 5.5.X



Found in


Issue ID




UnityWebRequest high CPU usage when using it in editor



Reproduction steps:
1. Open "" project
2. Open "UnityWebRequest" window from "Windows" menu
3. Click "New Web request" button.
4. Wait for few seconds.
5. If CPU usage returns to normal repeat from step 3.

NOTE: Entering play mode returns CPU usage to normal levels.

Expected result: Normal CPU usage
Actual result: High CPU usage

Reproduced on: 5.4.0f1, 5.3.5f1, 5.2.5p1

Comments (9)

  1. cozyurt_unity

    Jul 17, 2020 13:59

    kedi maması köpek maması

  2. Favo-Yang

    Jun 07, 2019 05:29

    Could be the busy wait consume all the cpu time? Try this instead,
    while (!request.isDone)

  3. huynh4_vng

    Sep 18, 2017 14:03

    Hi, I encountered this bug on 2017.1.1f1!!!!
    Please fix again! Thanks!
    (Windows 10 64bit)

  4. mWundke

    Aug 29, 2017 09:56

    For now I just make a small HEAD request before attempting to download the bundles, so it's a valid workaround atm.

  5. mWundke

    Aug 29, 2017 09:05

    Just reproduced it in 2017.1.0p4. While now it only happens when the AssetBundle failes to get downloaded or does not exists in the backend.

  6. ganaware

    Jan 10, 2017 10:27

    I encounterd this bug on 5.4.3p4 windows 64bit.
    On 5.4.3p2, there is no problem.

  7. LeekingWeng

    Jan 04, 2017 08:50

    This is very, very annoying! Still exists 5.5.0p3 windows editor.

  8. Kichang-Kim

    Dec 22, 2016 11:55

    This is very, very annoying! Still exists 5.4.3p3, 5.4.3p4 both windows and mac editor.

  9. ciela_spike

    Sep 29, 2016 08:05

    This may finally cause the editor to crash, which makes creating web service backed editor plugin difficult.

    Please fix this.

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