I just bought a CM15A with many WS467 and many remotes RF!
If I active a light on WS467 a delay is 1/10 sec
If i active a light with a software a delay is 1 sec
If i active a light with a PalmPad (HR12A) a delay is 1 sec
If i active a light with a chain remote (KR19A) a delay is 1 sec
If i active a light with a SlimSwitch (SS13A) a delay is 1 sec
If i active a light with a Infrared (IR543) a delay is 1/10 sec
Is it possible to reduce a delay when I use a RF remote ?
Unfortunately the answer is no.
Most of the delay is the amount of time it takes to transmit the command. The X10 powerline protocol is actually very slow. To understand why you are getting different delays you have to understand how the X10 protocol works.
To turn a specific light on or off two messages are needed. The first message is the address (housecode and unit code) and the second message is the action (turn the light on, off, bright or dim). Furthermore to ensure reliable operation, each message is repeated. So to turn a light at address A1 on, the following messages must be sent:
A1 - A1, A_ON - A_ON (every action is tied to a house code)
As you can see that the module doesn't know what to do until it has received the first A_ON command and since each message takes approximately 1/4 of a second to send, it takes about 3/4 of a second for the module to know what to do assuming there isn't any delay between you pressing the button on the remote and the transceiver starting to transmit the command.
Now you noted two cases where you get a faster responce, and there are good reasons why that is.
In the first case ("i active a light on WS467"), the WS467 is a receive only device and it doesn't have to send or receive any X10 commands and all it has to do is turn on, so it can do it very quickly.
In the last case ("i active a light with a Infrared (IR543)"), the IR543 sends the address and action commands separately so when you press the 1 button on the remote it will send the A1 - A1 commands and when you press the ON button it will send A_ON - A_ON. In this case it only takes about 1/4 of a second for the light to turn on because the address had already been sent before you pressed the ON button.
One other nice feature about the IR543 is that not only will it seem to respond faster to your commands but it will support grouping of commands so that if you for example press 1, 2, ON it will send A1 - A1, A2 - A2, A_ON - A_ON which will turn the modules on both A1 and A2 at the same time. On top of that it also allows much finer control of bright and dim commands. For various technical reasons with an RF remote you can only get about 8 brightness levels, but with an IR remote and the IR543, you can actually get (if you have very fast fingers) about 128 brightness levels using a little known feature called micro-dimming.