Set-PnPListItem executes with batching, but performance is terrible (~unbatched)

[bGlasson]

Batch updates for big SPO list work, but muuuuuch slower than expected.

2000 items took nearly an hour - so I made a cut down version and tested 50 items - that took 1min 36 to run.

It feels like batching isn't working. Any suggestions VERY welcome. Some potentially relevant context:

• SPO List is a doc library with 170k+ items total
• SPO List has many, many fields including lookups, multichoice and people pickers.
• 5 fields are updated in above tests (choice, multi-choice, text, choice, date

Sorry for including full code; I can't spot the issue and I'm sure (hoping!) its something easy!

UPDATE:
Tried the last few things that I didn't think should help.... and that didnt :(. Removing (or changing) the following had no effect:

• Connect-PnPOnline -UseWebLogin (-Interactve)
• Set-PnPListItem U-pdateType SystemUpdate
• Invoke-PnPBatch -Details

$now = Get-Date -Format "dd/MM/yy"
$runDate = [DateTime]::ParseExact($now, "dd/MM/yy", $null)
#start the time-to-complete clock 
$startTime = Get-Date
 
#Connect to PnP Online
Connect-PnPOnline -Url $SiteURL -UseWebLogin 

write-host "Script started at: " $startTime -ForegroundColor Cyan

$batch = New-PnPBatch

foreach ($item in $csv1)
{ 
    Set-PnPListItem -List $ListName -Identity $item."Id" -UpdateType SystemUpdate -Values @{

        "cjDocTypeV2" = $item."NEWcjDocTypeV2";
        "cjDocFlagsV2" = ($item."NEWcjDocFlagsV2").split(";#");
        "cjComments" = $item."NEWcjComments";
        "cjStatus" = $item."NEWcjStatus";
        "cjStatusChanged" = $runDate;
        }-Batch $batch
      
    }
 
# Execute the batch all at once
Invoke-PnPBatch -Batch $batch -Details
 
#stop the clock, calc time-to-complete tell me about it in console
$endTime = Get-Date
$totalTime = $endTime - $startTime
 
write-host "Total script run time: $($totalTime.Hours) hours, $($totalTime.Minutes) minutes, $($totalTime.Seconds) seconds" -ForegroundColor Cyan