根据我对表的了解，如果嵌套了太多的表，在呈现页面时浏览器会有很大的开销。

1 -浏览器必须等待呈现最终视图，直到整个表被加载。

2 - The algorithm to render the table is expensive and is not in a single go. The browser, as and when, gets the contents, will try to render calculating the content width and height. So, if you are having nested tables, say, the browser has received the first row and the 1st cell is having large amount of content and width and height not defined, it will calculate the width and will render the first row, In the mean while it gets the 2nd row will cell#2 having loads of content! It will now calculate the width for 2nd row cells.. What about the first ? It will calculate widths recursively. That's bad at client side. (To site an example) As a programmer, you'll optimize stuffs such as time to fetch data, optimized data structures and etc. You optimize things to complete on server side, say in2 secs, but end user in getting the final view in 8 secs. What is wrong here ? 1. May be network is slow! What if network is fine ? What is network is delivering the contents in next 1 sec ? Where is this extra 5 secs getting consumed ? Thing to worry about-- The browser might be taking lot of time in estimating and rendering the tables!

如何优化表? 如果你使用表格，我建议，总是定义单元格的宽度。这并不能保证浏览器会盲目地只取这个宽度，但会对浏览器决定初始宽度有很大的帮助。

但是，最后，div是CSS可以被浏览器缓存的好方法;而表没有缓存!

下面是我的程序员在一个类似的帖子中给出的答案

语义101

首先看一下这段代码，想想哪里出了问题……

class car {
    int wheels = 4;
    string engine;
}

car mybike = new car();
mybike.wheels = 2;
mybike.engine = null;

当然，问题在于自行车不是汽车。car类对于bike实例是不合适的类。代码没有错误，但是语义不正确。这对程序员的形象很不利。

语义102

现在将此应用于文档标记。如果您的文档需要显示表格数据，那么适当的标记将是<table>。但是，如果将导航放在表中，则滥用了<table>元素的预期用途。在第二种情况下，您没有表示表格数据—您(mis)使用<table>元素来实现表示目标。

结论

游客会注意到吗?不。你的老板在乎吗?也许吧。作为程序员，我们有时会偷工减料吗?当然。但是我们应该吗?不。如果使用语义标记，谁会受益?你，还有你的职业声誉。现在去做正确的事吧。

我尽量避免使用TABLEs，但是当我们设计复杂的表单，混合了多种控件类型和不同的标题位置，并对分组进行了非常严格的控制时，使用DIVs是不可靠的，甚至几乎是不可能的。

现在，我不会说这些表单不能重新设计以更好地适应基于DIV的布局，但是对于其中的一些表单，我们的客户坚决不改变以前版本(用经典ASP编写的)的现有布局，因为它与用户熟悉的纸质表单相似。

因为表单的表示是动态的(其中某些部分的显示是基于案例的状态或用户的权限)，所以我们使用一组堆叠的div，每个div包含一个由逻辑分组的表单元素组成的TABLE。TABLE的每一列都被分类，这样CSS就可以控制它们。这样，我们就可以关闭表单的不同部分，而不会出现在div中不是表来换行的问题。

I still don't quite understand how divs / CSS make it easier to change a page design when you consider the amount of testing to ensure the changes work on all browsers, especially with all the hacks and so on. Its a hugely frustrating and tedious process which wastes large amounts of time and money. Thankfully the 508 legislation only applies to the USA (land of the free - yeah right) and so being as I am based in the UK, I can develop web sites in whatever style I choose. Contrary to popular (US) belief, legislation made in Washington doesn't apply to the rest of the world - thank goodness for that. It must have been a good day in the world of web design the day the legislation came into force. I think I'm becoming increasingly cynical as I get older with 25 years in the IT industry but I feel sure this kind of legislation is just to protect jobs. In reality anyone can knock together a reasonable web page with a couple of tables. It takes a lot more effort and knowledge to do this with DIVs / CSS. In my experience it can take hours and hours Googling to find solutions to quite simple problems and reading incomprehensible articles in forums full of idealistic zealots all argueing about the 'right' way to do things. You can't just dip your toe in the water and get things to work properly in every case. It also seems to me that the lack of a definitive guide to using DIVS / CSS "out of the box", that applies to all situations, working on browsers, and written using 'normal' language with no geek speak, also smells of a bit of protectionism. I'm an application developer and I would say it takes almost twice as long to figure out layout problems and test against all browsers than it does to create the basic application, design and implement business objects, and create the database back end. My time = money, both for me and my customers alike so I am sorry if I don't reject all the pro DIV / CSS arguments in favour of cutting costs and providing value for money for my customers. Maybe its just the way that developers minds work, but it seems to me far easier to change a complex table structure than it is to modify DIVs / CSS. Thankfully it now appears that a solution to these issues is now available - its called WPF.

显而易见的答案:参见CSS Zen Garden。如果你告诉我你可以很容易地用基于表格的布局做同样的事情(记住- HTML没有改变)，那么无论如何都要使用表格来布局。

另外两个重要的事情是可访问性和搜索引擎优化。

两者都关心信息以何种顺序呈现。如果基于表格的布局将导航放在页面上第二个嵌套表格的第2行的第3个单元格中，则无法轻松地将导航显示在页面顶部。

所以你的答案是可维护性，可访问性和SEO。

不要偷懒。即使事情有点难学，也要用正确的方式去做。

I have found that even with the best planning divs come up short in several respects. For instance. there is no way with divs to have a bottom bar that always sits at the bottom of the browser, even when the rest of the content does not go to the bottom of the browser. Also, you cannot elegantly do anything better than three columns, and you cannot have columns that grow and shrink according the the width of their content. In the end, we try to use divs first. However, we will not limit our html designs based on some religious content vs layout ideal.