Make a Folder with Thousands of Files Open Fast

A folder that takes seconds to enumerate has a count and a size. Both numbers decide whether the cause is the view, the disk or the indexer.

$p = 'C:\Users\me\Downloads'
(Get-ChildItem $p -Force | Measure-Object).Count
(Get-ChildItem $p -Force | Measure-Object -Property Length -Sum).Sum
Measure-Command { Get-ChildItem $p -Force | Out-Null } | Select-Object TotalMilliseconds

A folder optimised for pictures or music makes Explorer read dimensions and tags for every file. The template is stored per folder in the shell bags.

# right-click the folder > Properties > Customize
# Optimize this folder for: General items
# tick Apply this template to all subfolders
Get-ItemProperty 'HKCU:\Software\Microsoft\Windows\Shell\Bags\*\Shell' -ErrorAction SilentlyContinue | Select-Object -First 3 * -ExcludeProperty PS*

Large icons and extra-large icons force a thumbnail read for each file. Details or List shows names only, which is the difference between one and twenty thousand reads.

# Explorer > View > Details (or List)
# View > untick Item check boxes and File name extensions if they slow the first paint
Get-ItemProperty 'HKCU:\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced' | Select-Object IconsOnly,ListviewAlphaSelect,ListviewShadow

**IconsOnly = 1** disables previews and thumbnails for the current user. It affects all folders, so it is the right switch only when previews are not useful to you.

Set-ItemProperty 'HKCU:\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced' -Name IconsOnly -Value 1 -Type DWord
Stop-Process -Name explorer -Force
Get-ItemProperty 'HKCU:\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced' | Select-Object IconsOnly

The indexer reads every file to build content and property entries. A folder of transient files gains nothing from being indexed.

Get-ItemProperty 'HKLM:\SOFTWARE\Microsoft\Windows Search' | Select-Object SetupCompletedSuccessfully
Get-ChildItem 'HKLM:\SOFTWARE\Microsoft\Windows Search\CrawlScopeManager\Windows' -ErrorAction SilentlyContinue | Select-Object -First 5 Name
# Indexing Options > Modify > untick the folder

Explorer caches the enumeration per folder. A second open should be fast; if it is not, the cause is the disk or the antivirus scanning every access.

Measure-Command { Start-Process explorer.exe -ArgumentList 'C:\Users\me\Downloads' } | Select-Object TotalMilliseconds
Get-Counter '\PhysicalDisk(*)\Avg. Disk sec/Read' -SampleInterval 1 -MaxSamples 3 | Select-Object -ExpandProperty CounterSamples | Select-Object InstanceName,CookedValue
Get-MpPreference | Select-Object -ExpandProperty ExclusionPath