The need for speed

[nortkele]

Hello  prokops,
my online shop GTmetrix score is : 97/88.
http://www.1001avtochasti.com
inside we have 3000 products.
It is based on : Joomla! 3.4.0 ; Virtuemart VirtueMart 3.0.14 . Web site is hosted on own server xampp with php 5.6. Template - core joomla template Protostar. Template is Re developed by me. W3Cvalidation.
Best regards

[servlet]

Dear Studio 42, thanks for your comments,
but what makes you say that it is "badly optimized"? image size?the product is loaded by costumer... (i could optimized all the media on the webserver...)  Gzip compression is anable, JCH is enable (not professional only starter plugin)
What makes a best "well optimized" site? what other?? the cache is enable (YES conservative and for some module is disabled) and plugin system cache disable (if I enable make problem and timeout errors)

the products are not structured in a parent/child,
each is an independent item and is connected from 1 to 4 categories
every product has either 1 or 3 price list,
all have relations with other products (necklace management magazine): relationship management such as: magazine -> 01 month, 02 month, 03 month, for each month, week 01, week 02, dossier ... 1, 2, 3, ...
what I believe is the cause of the major problems are the relationships with manufacturers, and specifically "authors", each has 1 to 9 assignments

the only plug-in used on site front-end is
flexibletemplate for VM,
Nextend Accordion Menu V9
on homepage is BT Product Slider
propayment
nonumber extensions

..all extension (not free) approved by official extension of VM...

EDIT: I have also try to exclude from column search the manufacturer, id sku, GTIN(isbn), and use only title and the short description (update this info with the names of manufacturers related with the product...), but nothing change on the time of response of search module.

Other?

If you have big category menu loaded via Nextend Accordion Menu V9 without cache you will have slow load...
Activate cache by clicking CONFIGURE inside module options...