I think that your page runs about as fast as I'd expect with six layers
of tiles (one Google layer and 5 custom layers).
The page runs slightly faster at low zoom levels because some of those
layers return blank-tile.png for tiles outside the supported region.
When you zoom in, there's real data for every tile.
I'd suggest either only running one or two custom layers at the same
time.
The ultimate solution would be to write a tile server that blends the
graphics of the five layers for you, and returns a single layer of
tiles. Your getTileUrl would send it a list of the 5 opacity settings as
well as the tile location info in the tile request and it would use gd
to blend the imagery on the server side and return a single tile.
I also notice that the Internet latency of connections to
www.williams.edu is rather variable. Sometimes it will respond in 100ms,
but it goes through patches when it takes 300ms to get a response. That
all adds up when you're requesting about 80 tiles.
Note that the vast majority of the tile fetch time in this case is taken
up with the latency. Fetching an image "from cold" has five stages:
DNS lookup
Establish connection
Latency
Content Download
In this case, because there are many calls to the same domain, there's
only one DNS lookup for the domain, and once established, the
connections are kept alive. Your custom tiles typically contain very
little data, so the latency dominates. In this snippet from a pagetest
report for a single DINOVISIT tile the latency is called "Time to First
Byte":
URL:
http://www.williams.edu/Economics/ArtsEcon/mappages/Kenosha/DINOVISIT1-ti
les/tqsqttttrsq.png
Host: www.williams.edu
IP: 137.165.6.26
Location: Williamstown, MA*
Error/Status Code: 200
Start Offset: 3.276 s
Time to First Byte: 312 ms
Content Download: 4 ms
Bytes In (downloaded): 1.7 KB
Bytes Out (uploaded): 0.7 KB
--
http://econym.org.uk/gmap
The Blackpool Community Church Javascript Team
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Google Maps API" group.
To post to this group, send email to [email protected]
To unsubscribe from this group, send email to [EMAIL PROTECTED]
For more options, visit this group at
http://groups.google.com/group/Google-Maps-API?hl=en
-~----------~----~----~----~------~----~------~--~---
