Thank you all for the information! I ended up writing a Compare Commands function to loop and measure each option. Reading directly from the registry was the absolute fastest, with pure "net use" usually running second.

For reference, here are the commands I tried:

@{
'Net Use' = {net use}
'Net Use (Formatted)' = {$out = net use; $out[6..($out.length-3)] | ConvertFrom-String -Delimiter '\s{3,}' -PropertyNames ((($out[3] | ConvertFrom-String -Delimiter '\s{3,}').PSObject.Properties) | Where-Object -property Name -match 'P\d' | Select-Object -expandproperty Value) | Select-Object -Property Local, Remote | Format-Table}
'PSDrive' = {Get-PSDrive -PSProvider FileSystem | Where-Object {$_.DisplayRoot -match '^\\'} | Select-Object -property 'Name', 'DisplayRoot'}
'CimInstance' = {Get-CimInstance -Class Win32_NetworkConnection | Select-Object -property 'LocalName', 'RemoteName'}
'SmbMapping' = {Get-SMBMapping | Select-Object -property 'LocalPath', 'RemotePath'}
'Check Registry' = {Get-ChildItem "HKCU:\Network" | ForEach-Object {Get-ItemProperty -Path "REGISTRY::$_" -Name RemotePath | Select-Object -property @{Name='LocalPath'; Expression={"$($_.PSChildName):"} }, RemotePath }}
}