NopCommerce 4.40.4 is faster except unknown CPU spikes

Recently we have upgraded to 4.40,4 for https://bebooks.com.au. It's faster. That's good. But we don't know why there are too many CPU spikes, see https://bettereducation.com.au/forum/Uploads/DirectUpload/nop4.40.4CpuSpikes3days1minInterval.PNG

We don't have many plugins installed, see the following list. They should be the safe and reliable ones.
  "InstalledPlugins": [
    {
      "SystemName": "Payments.PayPalCommerce",
      "Version": "1.00"
    },
    {
      "SystemName": "Payments.PayPalStandard",
      "Version": "1.66"
    },
    {
      "SystemName": "DiscountRequirement.MustBeAssignedToCustomerRole",
      "Version": "1.36"
    },
    {
      "SystemName": "Pickup.PickupInStore",
      "Version": "1.39"
    },
    {
      "SystemName": "Shipping.FixedByWeightByTotal",
      "Version": "2.28"
    },
    {
      "SystemName": "Widgets.GoogleAnalytics",
      "Version": "1.67"
    },
    {
      "SystemName": "ExternalAuth.Facebook",
      "Version": "1.68"
    }
  ],

We didn't change the source code except for supporting external image URLs.

Please note that running debug build in Visual Studio on local machine, the CPU in diagnostics tools seems normal. It is within 10% of all processors.

We don't think that the CPU spikes on Azure are caused by crawlers because our other site on Azure doesn't have the problem even though  it allows more frequent crawling..

In the past, we collected memory dumps but didn't find anything wrong. It just points to the platform (mainly azure) as the hot path.  But we don' think it's the fault of Azure. However we don't know what the cause is. Please let us know if you have any suggestions. Thank you.

j2bmw wrote:

How are you running nop, in a VM or app service? I have one of nop 4.40.4 websites installed recently on an azure VM and haven't noticed any CPU spikes, it happily runs. I haven't seen any major memory issues either after taking a mem dump.

You may want to run diags log to see which apps are causing the CPU spikes.

Hi Jayc,

Thanks for your reply.

I run the app on Azure App Service. The past memory dumps didn't help me.  I will do more memory dumps.