I'm sending a new patch in the attachment. I've also instrumented the function using the `elp' package, here are the results:

Function Name           Call Count  Elapsed Time  Average Time
orgtbl-to-table.el-old  1001        2.6707780000  0.0026681098
orgtbl-to-table.el-new  1001        2.4684200000  0.0024659540

New version is indeed a little bit faster.

Best, Jakub