[Vb.net] Eventlog Watcher Service becomes unresponsive after large amount of entries

This is the situation:
I have written a Windows Service that monitors the Domain Controllers Security eventlog for certain events.
It filters the eventmessages and sends email if a filter is matched.

The service runs fine until our HR-->Active Directory import runs.
This adds ca. 2000 events to the Security eventlog within 2 seconds.
After this, the service still runs, but doesn't respond to new events anymore.
Hopefully someone can point me in the right direction to solve this

Imports System.Threading
Imports System.Net.Mail
Imports System.Security.Principal

Public Class EventLogWatcherService
    Private Shared signal As AutoResetEvent

    Protected Overrides Sub OnStart(ByVal args() As String)
        ' This is where the service starts 

        'Start the Event Log Watcher Service as a new thread
        Dim workerThread = New Thread(AddressOf WatchEventLog)
        workerThread.Start()

        'Write start message to Eventlog
        WriteLogMessage("Service Started", EventLogEntryType.Information)
    End Sub

    Public Sub WatchEventLog()
        'Set new event
        signal = New AutoResetEvent(False)

        'Connect to the OS-Security Eventlog
        Dim logwatcherlog = New EventLog("Security", ".", "LogMonitoringService")
        logwatcherlog.Source = "LogMonitoringService"

        'Add event handler to the Security Eventlog. This triggers at new events
        AddHandler logwatcherlog.EntryWritten, New System.Diagnostics.EntryWrittenEventHandler(AddressOf EventLog1_EntryWritten)
        logwatcherlog.EnableRaisingEvents = True

        'Wait for Event
        signal.WaitOne()
    End Sub

    Public Sub EventLog1_EntryWritten(ByVal [source] As Object, ByVal e As entryWrittenEventArgs)
        'Check the Events on EventID's. On match a new thread is fired to handle this event.
        If e.Entry.InstanceId = "4728" Or e.Entry.InstanceId = "4729" Then
            Dim thread As New Threading.Thread(AddressOf FoundEventToHandle)
            thread.Start(e)
        End If
    End Sub

    Public Sub FoundEventToHandle(ByVal e As EntryWrittenEventArgs)
            ‘Filters the eventmessage and sends an email on a filter match.

            '** WHEN HR-->AD IMPORT IS RUN, THIS PART ISN"T REACHED**
            
            'Dispose the current Entry to prevent unresponive service
            e.Entry.Dispose()

           'Sleep short and Signal for complete
           Thread.Sleep(1)
           signal.Set()
    End Sub