If the latency optimization doesn't work, then it's all depending on the protocol being spoken:
SMB latency optimization:
Failed oplock acquisition.
Write-behind cancellation.
Unsupported SMB version.
Unsupported SMB server.
If the data is signed and the Active Directory integration failed.
Just an inefficient approach: Copy a roaming profile consisting of a lot of directories and small files instead of copying one large file and decompressing it locally.
MAPI latency optimization:
If the data is encrypted and the Active Directory integration failed.
For MAPI-OA, is the SSL optimization working?
HTTP latency optimization:
Latency optimization discontinues for the rest of the requests when one fails.
If Full Transparency is used, every new HTTP session needs to be auto-discovered and inner channel being setup before the requests are forwarded.
+ ?
NFS latency optimization:
Unsupported NFS version.
Unsupported authentication encryption mechanism.
MS-SQL:
Unsupported MS-SQL version.
Lotus Notes:
The traffic is encrypted and the latency optimization is not configured for it.
SSL pre-optimization:
The maximum number of optimized TCP sessions being SSL encrypted is about 40-50% of the hardware specified amount of TCP sessions the machine is capable of.