Advanced GB 2.3.1 Complex Query with long DB

I detected an issue with Advanced Guestbook 2.3.1 . I have one Data base with 13,456 entrys in book_com and 7833 entrys in book_data , at first all was working very fast but now that I have this big Data Base it always take a lot of time in process one new entry frop addentry.php

2347 | gentezac_chis | localhost | gentezac_chismes | Query | 75 | Copying to tmp table | select x.*, y.p_filename, y.width, y.height, z.comments from book_data x left join book_pics y on (x |

you can try to if you enter to:

http://www.gentezac.com.mx/modules.php?name=guestbook

and try to put a new entry.

Thanks

This is my server Information:
Note it was tested in two diferent servers:

InformationProcessor #1 Vendor: GenuineIntel
Processor #1 Name: Intel(R) Celeron(R) CPU 2.40GHz
Processor #1 speed: 2390.335 MHz
Processor #1 cache size: 128 KB

Memory InformationMemory: 512356k/524288k available (3247k kernel code, 11544k reserved, 1038k data, 400k init, 0k highmem)

Processor InformationProcessor #1 Vendor: GenuineIntel
Processor #1 Name: Intel(R) Pentium(R) III CPU 1200MHz
Processor #1 speed: 1196.981 MHz
Processor #1 cache size: 256 KB

Memory InformationMemory: 904488k/917504k available (1550k kernel code, 12632k reserved, 311k data, 128k init, 0k highmem)