Percent sign % not working in crontab
% is a special character for crontab. From man 5 crontab:
The "sixth" field (the rest of the line) specifies the command to be run. The entire command portion of the line, up to a newline or a "%" character, will be executed by /bin/sh or by the shell specified in the SHELL variable of the cronfile. A "%" character in the command, unless escaped with a backslash (\), will be changed into newline characters, and all data after the first % will be sent to the command as standard input.
So you need to escape the % character:
curl -w "%{time_total}\n" -o /dev/null -s http://myurl.com >> ~/logto
curl -w "\%{time_total}\n" -o /dev/null -s http://myurl.com >> ~/log ^