I am in process of setting up a catalog website and it has some 1.5 Lac products. I will write some script to import all the products but I am not sure whether WordPress will be able to handle such a large amount of posts.
Have any one imported so many posts in WordPress and how much is the degrade in the performance of the website. And any solutions to fix that performance.
Can any one suggest any other CMS or framework to handle such a large data?
The performance of WordPress does not depend on the number of posts. It depends on the server performance (how fast can PHP scripts be executed). And the performance of the MySQL Server.
The server performance is normally no problem if you got enough memory. The bottleneck is in most cases the MySQL server and the connection to it. Sometimes a misconfigured MySQL server can slow down your database queries. MySQL is made to handle very large databases, it makes no difference if there are 15 or 15 million posts. wordpress.com is made with WordPress and there are definitivly a lot of post to handle.
But this is all out of scope of this page, it has nothing to do with WordPress.
WordPress itself cann be slowed down by bad written plugins and themes. Such who make a lot of (senseless) database queries. There is no other way then uninstall problematic plugins and/or themes and use better ones.
It depends on which language you use for your script. PHP is not the first choice for such a job. A MySQL script would be the better choice and can do the job much faster.
WordPress certainly can handle that number of posts on a single installation, but there are factors to consider. How well it performs will depend on a number of factors, particularly what plugins you install or the theme you use.
Certain database tables will grow significantly with the number of posts, for example:
Make sure to add something like W3TC to help with the performance, although it’s effects will be likely more limited for this kinda of pattern. It works better for sites with high traffic to a small number of posts.
Source: I maintain a fairly active news site with 160k posts on a single installation, and performance issues often arise.