Anonymous load takes LONGER than authenticated!

I appear to have misconfigured something, somewhere. Assume I know nothing and could have overlooked something very basic.

The problem;

• My authenticated users can load my heaviest page in a couple of seconds.
• My anonymous users with a cache hit can load it in less than a second.
• My anonymous users on a cold cache wait 45 seconds for the first byte to load.

This only seems to be an issue on my <front> pages, across all of my subdomains. I've used Domain Access to inform drupal that <front> is a Views page with the path /frontpage.

All of my taxonomy and node pages do not seem to suffer from the same issue.

I've tried enabling/disabling Global Redirect with no effect.

I'm using Memcache and have tried disabling and enabling stampede protection and memcache lock implementation - no effect.

I'm using APC and HTTPRL.

I'm on a fairly fast VPS. I have 500+ subdomains set up with a wildcard DNS.

What gives!? Is this some kind of snag in the redirect? Why is it only affecting anonymous users on a cold cache? How do I fix this?

Thank you SO MUCH for any input.

Header info for the 45 second delay:

Error/Status Code: 200
Client Port: 59718
Request Start: 0.064 s
Initial Connection: 36 ms
Time to First Byte: 43921 ms
Content Download: 49 ms
Bytes In (downloaded): 12.2 KB
Bytes Out (uploaded): 0.4 KB
Request Headers:
GET /frontpage?keys=&page=316 HTTP/1.1
Host: subdomain.domain.com
Connection: keep-alive
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,/;q=0.8
Upgrade-Insecure-Requests: 1
User-Agent: Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/44.0.2403.130 Safari/537.36 PTST/229
Accept-Encoding: gzip, deflate, sdch
Accept-Language: en-US,en;q=0.8
Response Headers:
HTTP/1.1 200 OK
Date: Thu, 06 Aug 2015 16:13:24 GMT
Server: Apache
X-Drupal-Cache: MISS
Expires: Sun, 19 Nov 1978 05:00:00 GMT
Cache-Control: public, max-age=86400
Content-Language: en
X-Generator: Drupal 7 (http://drupal.org)
Last-Modified: Thu, 06 Aug 2015 16:13:24 GMT
Vary: Cookie,Accept-Encoding
Content-Encoding: gzip
Connection: close
Transfer-Encoding: chunked
Content-Type: text/html; charset=utf-8