Lots of traffic by wsus not controlled

Hello everyone.

For the distribution of updates in our company we are using WSUS. This is a company with 2000 offices and about 8 Windows 7 computers in each office. We have 6 W2008R2 servers balanced with F5 serving WSUS, and more or less, the traffic generated by WSUS is controlled by limitations in BITS. But nevertheless, there are 2 network traffic spikes that last about 10 minutes and almost completely stop office on 2 occasions during the morning. When turning on computers at 8 o'clock and 11 in the morning. That is the time that is set to install updates. And we don't know how to limit that traffic. In these graphs it looks:

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You can see that the traffic is generated by the post 10.205.16.145. The configuration of this computer is this:

C:\Temp>verwsus 10.205.16.145

HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows\WindowsUpdate
    WUServer    REG_SZ    http://ptwsus
    WUstatusServer    REG_SZ    http://ptwsus
    TargetGroup    REG_SZ    W7PRO0
    TargetGroupEnabled    REG_DWORD    0x1
    ElevateNonAdmins    REG_DWORD    0x1

HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows\WindowsUpdate\AU
    UseWUServer    REG_DWORD    0x1
    AutoInstallMinorUpdates    REG_DWORD    0x1
    NoAutoRebootWithLoggedOnUsers    REG_DWORD    0x1
    NoAutoUpdate    REG_DWORD    0x0
    AUOptions    REG_DWORD    0x4
    ScheduledInstallDay    REG_DWORD    0x2
    ScheduledInstallTime    REG_DWORD    0xb
    DetectionFrequencyEnabled    REG_DWORD    0x0
    RescheduleWaitTimeEnabled    REG_DWORD    0x0
    NoAUShutdownOption    REG_DWORD    0x1
    NoAUAsDefaultShutdownOption    REG_DWORD    0x1


HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\BITS
    EnableBitsMaxBandwidth    REG_DWORD    0x1
    MaxBandwidthValidFrom    REG_DWORD    0x7
    MaxBandwidthValidTo    REG_DWORD    0xa
    MaxTransferRateOnSchedule    REG_DWORD    0x0
    MaxTransferRateOffSchedule    REG_DWORD    0xa
    EnablePeercaching    REG_DWORD    0x1

But in the WindowsUpdate.log nothing appears during this period. (8:06 to 8:12)???

2013-08-2008:06:58:077892145cPT+++++++++++  PT: Synchronizing server updates  +++++++++++
2013-08-2008:06:58:077892145cPT + ServiceId = {3DA21691-E39D-4DA6-8A4B-B43877BCB1B7}, Server URL = http://ptwsus/ClientWebService/client.asmx
2013-08-2008:06:58:398892145cPTWARNING: Cached cookie has expired or new PID is available
2013-08-2008:06:58:399892145cPTInitializing simple targeting cookie, clientId = ac76cc14-1088-41ce-ada4-e708d17b9277, target group = W7PRO0, DNS name = vid42040.oficinas.grupo.cm.es
2013-08-2008:06:58:399892145cPT Server URL = http://ptwsus/SimpleAuthWebService/SimpleAuth.asmx
2013-08-2008:12:02:183892145cPT+++++++++++  PT: Synchronizing extended update info  +++++++++++
2013-08-2008:12:02:183892145cPT + ServiceId = {3DA21691-E39D-4DA6-8A4B-B43877BCB1B7}, Server URL = http://ptwsus/ClientWebService/client.asmx
2013-08-2008:12:09:005892145cAgent * Added update {9D14BFBD-45F3-4886-BBF8-817E2AE15A97}.105 to search result
2013-08-2008:12:09:005892145cAgent * Added update {FC5608E4-A70D-4344-B358-2847F4A57434}.201 to search result
2013-08-2008:12:09:005892145cAgent * Added update {0B92ACCC-057D-408A-8E6E-0867F21F015F}.202 to search result
2013-08-2008:12:09:005892145cAgent * Added update {DD0187ED-CDE7-4117-B1D2-D8DD119B55E7}.202 to search result
2013-08-2008:12:09:005892145cAgent * Added update {BBF2E903-A598-4830-B676-98DF3A6E01D4}.200 to search result
2013-08-2008:12:09:005892145cAgent * Added update {E31F669C-CC33-40A3-954C-47BD3C6FA68E}.202 to search result
2013-08-2008:12:09:005892145cAgent * Added update {14C9B803-8F12-45A5-8F00-936B6EC937EE}.202 to search result
2013-08-2008:12:09:005892145cAgent * Added update {8E205F7F-E982-43EA-A762-4EC4EB4F2796}.201 to search result
2013-08-2008:12:09:005892145cAgent * Added update {5DD85911-981D-4A07-8B35-35619EA4DA29}.200 to search result
2013-08-2008:12:09:006892145cAgent * Added update {B5C84092-6294-4358-86EB-7D743AABD04A}.201 to search result
2013-08-2008:12:09:006892145cAgent * Added update {275DDA53-C100-4F18-8DC0-7C81031E2E13}.203 to search result
2013-08-2008:12:09:006892145cAgent * Found 11 updates and 74 categories in search; evaluated appl. rules of 951 out of 1421 deployed entities
2013-08-2008:12:09:039892145cAgent*********
2013-08-2008:12:09:039892145cAgent**  END  **  Agent: Finding updates [CallerId = AutomaticUpdates]
2013-08-2008:12:09:039892145cAgent*************

The BITS traffic as you see is limited 0KBps 7:00 a.m. to 10:00 a.m. and 10kbps remaining hours. We are also using peercaching. But I don't know what's doing wsus at that time, and how to limit, because it's eating all the bandwidth of the office. Can anyone help?

Thanks in advance.

Greetings.