Thank you for the post.
What are the full system specifications for the host computer?
WebDirect is memory and process intensive. Here are our recommended specifications:
RAM: 8 GB
Hard Drive: 80 GB or more, dependent on file size, requires minimum 10 GB free space
"For best performance, run FileMaker Server on a dedicated machine reserved for use as a database server. When FileMaker Server is hosting many clients or a large number of database files, it uses a high level of processor, hard disk, and network capacity. Other processor-intensive software or heavy network traffic on the same machine will cause FileMaker Server to run more slowly and degrade the performance for FileMaker clients."
For more, review "Considering performance" on page 10 of the FileMaker Server 13 Getting Started Guide.