looking at the nodes' scanner page, is there anything can tell us about CPU speed of a node?
Not really, no.
It could be "GBTL =Get Block Template Latency," but I do not know what dose it mean. any idea?
GBTL is the amount of time that it takes for p2pool to get a response back from bitcoind when it asks for a new block template (i.e. a new batch of transactions). It is a poor indicator of CPU performance. It mostly just reflects block size. If the CPU is way too slow for p2pool, then this number will climb to 200 ms or longer (possibly even several seconds), but if the CPU is just a bit too slow, it won't show much at all.
That was written many years ago, back when block sizes were under 100 kB, long before p2pool started to show the CPU performance bottleneck.