add fast str casts to readme

Author: Andy Landy

README.md

@@ -1,7 +1,7 @@
 ![Example](https://raw.githubusercontent.com/andy-landy/traceback_with_variables/master/header.png)
 
 <h2 align="center">Python Traceback (Error Message) Printing Variables</h2>
-<p align="center">Very simple to use, but versatile when needed. Try for debug and keep for small-scale production.</p>
+<p align="center">Very simple to use and fast, but versatile when needed. Try for debug and keep for small-scale production.</p>
 
 <p align="center">
 <a href="https://github.com/andy-landy/traceback_with_variables/actions"><img alt="Actions Status" src="https://github.com/andy-landy/traceback_with_variables/workflows/tests/badge.svg"></a>
@@ -262,7 +262,14 @@ Using a logger [<a href="https://github.com/andy-landy/traceback_with_variables/
      step 5: Examine the printouts and possibly add some more info (then go back to step 2). \
      step 6: Erase all recently added printouts, logging and exception messages. \
      step 7: Go back to step 1 once bugs appear.
-     
+
+
+* — Is it slow? I have huge lists and dicts and data objects!
+
+    Data size doesn't matter, the objects are printed smartly, so only the result suffix and prefix are generated:
+       e.g. `list(range(100000000))` becomes `[0, 1, 2, ...9998, 99999999]`
+    Use `fmt`'s `.max_value_str_len`, and `.rel_ellipsis_pos` (0.0 to 1.0) to tweak the output.
+ 
 
 ### Examples and recipes
 

README.tmpl

@@ -1,7 +1,7 @@
 ![Example]({{ content_url }}/header.png)
 
 <h2 align="center">Python Traceback (Error Message) Printing Variables</h2>
-<p align="center">Very simple to use, but versatile when needed. Try for debug and keep for small-scale production.</p>
+<p align="center">Very simple to use and fast, but versatile when needed. Try for debug and keep for small-scale production.</p>
 
 <p align="center">
 <a href="{{ repo_url }}/actions"><img alt="Actions Status" src="{{ repo_url }}/workflows/tests/badge.svg"></a>
@@ -262,7 +262,14 @@ Using a logger [<a href="{{ examples_code_url }}/log_for_function.py">with a dec
      step 5: Examine the printouts and possibly add some more info (then go back to step 2). \
      step 6: Erase all recently added printouts, logging and exception messages. \
      step 7: Go back to step 1 once bugs appear.
-     
+
+
+* — Is it slow? I have huge lists and dicts and data objects!
+
+    Data size doesn't matter, the objects are printed smartly, so only the result suffix and prefix are generated:
+       e.g. `list(range(100000000))` becomes `[0, 1, 2, ...9998, 99999999]`
+    Use `fmt`'s `.max_value_str_len`, and `.rel_ellipsis_pos` (0.0 to 1.0) to tweak the output.
+ 
 
 ### Examples and recipes