diff --git a/lib/controller/checks.py b/lib/controller/checks.py
index 8d5d3569a..e5babab32 100644
--- a/lib/controller/checks.py
+++ b/lib/controller/checks.py
@@ -14,6 +14,7 @@ import time
 from difflib import SequenceMatcher
 
 from lib.core.agent import agent
+from lib.core.common import average
 from lib.core.common import beep
 from lib.core.common import calculateDeltaSeconds
 from lib.core.common import extractRegexResult
@@ -45,7 +46,8 @@ from lib.core.exception import sqlmapSiteTooDynamic
 from lib.core.exception import sqlmapUserQuitException
 from lib.core.session import setString
 from lib.core.session import setRegexp
-from lib.core.settings import TIME_MIN_DELTA
+from lib.core.settings import MIN_DURATION_RATIO
+from lib.core.settings import TIME_TOLERANCE
 from lib.request.connect import Connect as Request
 from lib.request.templates import getPageTemplate
 from plugins.dbms.firebird.syntax import Syntax as Firebird
@@ -352,23 +354,17 @@ def checkSqlInjection(place, parameter, value):
                         # Perform the test's request and check how long
                         # it takes to get the response back
                         start = time.time()
-                        _ = Request.queryPage(reqPayload, place)
+                        _ = Request.queryPage(reqPayload, place, noteResponseTime = False)
                         duration = calculateDeltaSeconds(start)
-
-                        trueResult = (check.isdigit() and duration >= int(check)) or (check == "[DELAYED]" and duration >= max(TIME_MIN_DELTA, kb.responseTime))
+ 
+                        trueResult = (check.isdigit() and abs(duration - int(check) - average(kb.responseTimes)) < TIME_TOLERANCE)\
+                            or (check == "[DELAYED]" and duration >= MIN_DURATION_RATIO * max(kb.responseTimes))
 
                         if trueResult:
-                            start = time.time()
-                            _ = Request.queryPage(reqPayload, place)
-                            duration = calculateDeltaSeconds(start)
+                            infoMsg = "%s parameter '%s' is '%s' injectable " % (place, parameter, title)
+                            logger.info(infoMsg)
 
-                            trueResult = (check.isdigit() and duration >= int(check)) or (check == "[DELAYED]" and duration >= max(TIME_MIN_DELTA, kb.responseTime))
-
-                            if trueResult:
-                                infoMsg = "%s parameter '%s' is '%s' injectable " % (place, parameter, title)
-                                logger.info(infoMsg)
-
-                                injectable = True
+                            injectable = True
 
                         # Restore value of socket timeout
                         socket.setdefaulttimeout(popValue())
@@ -763,9 +759,7 @@ def checkConnection(suppressOutput=False):
         logger.info(infoMsg)
 
     try:
-        start = time.time()
         page, _ = Request.queryPage(content=True)
-        kb.responseTime = time.time() - start
         kb.originalPage = kb.pageTemplate = page
     except sqlmapConnectionException, errMsg:
         errMsg = getUnicode(errMsg)
diff --git a/lib/core/common.py b/lib/core/common.py
index ef085000f..f78030b75 100644
--- a/lib/core/common.py
+++ b/lib/core/common.py
@@ -1276,12 +1276,17 @@ def readXmlFile(xmlFile):
     xfile.close()
     return retVal
 
-def calculateDeltaSeconds(start, epsilon=0.1):
+def average(values):
     """
-    Returns elapsed time from start till now (including expected
-    error set by epsilon parameter)
+    Computes the arithmetic mean of a list of numbers.
     """
-    return time.time() - start - kb.responseTime + epsilon
+    return sum(values, 0.0) / len(values)
+
+def calculateDeltaSeconds(start):
+    """
+    Returns elapsed time from start till now
+    """
+    return time.time() - start
 
 def initCommonOutputs():
     kb.commonOutputs = {}
diff --git a/lib/core/option.py b/lib/core/option.py
index 6c26c23a2..69d888f65 100644
--- a/lib/core/option.py
+++ b/lib/core/option.py
@@ -1173,7 +1173,7 @@ def __setKnowledgeBaseAttributes():
     kb.proxyAuthHeader = None
     kb.queryCounter    = 0
     kb.redirectSetCookie = None
-    kb.responseTime    = 0
+    kb.responseTimes   = []
     kb.resumedQueries  = {}
     kb.retriesCount    = 0
     kb.tamperFunctions = []
diff --git a/lib/core/settings.py b/lib/core/settings.py
index b6168d086..b4dedbfdb 100644
--- a/lib/core/settings.py
+++ b/lib/core/settings.py
@@ -48,8 +48,9 @@ DUMP_STOP_MARKER    = "__STOP__"
 
 PAYLOAD_DELIMITER  = "\x00"
 
-# minimum difference of loading time in seconds for delayed time payloads
-TIME_MIN_DELTA     = 2
+# time testing settings
+TIME_TOLERANCE     = 0.5
+MIN_DURATION_RATIO = 1.5
 
 # System variables
 IS_WIN             = subprocess.mswindows
diff --git a/lib/request/connect.py b/lib/request/connect.py
index c0332f753..8850f5541 100644
--- a/lib/request/connect.py
+++ b/lib/request/connect.py
@@ -320,7 +320,7 @@ class Connect:
         return page, responseHeaders
 
     @staticmethod
-    def queryPage(value=None, place=None, content=False, getSeqMatcher=False, silent=False, method=None, auxHeaders=None, response=False, raise404 = None):
+    def queryPage(value=None, place=None, content=False, getSeqMatcher=False, silent=False, method=None, auxHeaders=None, response=False, raise404 = None, noteResponseTime = True):
         """
         This method calls a function to get the target url page content
         and returns its page MD5 hash or a boolean value in case of
@@ -339,6 +339,7 @@ class Connect:
         uri         = None
         raise404    = place != PLACE.URI if raise404 is None else raise404
         toUrlencode = { PLACE.GET: True, PLACE.POST: True, PLACE.COOKIE: conf.cookieUrlencode, PLACE.UA: True, PLACE.URI: False }
+        start       = time.time()
 
         if not place:
             place = kb.injection.place
@@ -412,6 +413,9 @@ class Connect:
             if conf.cj:
                 conf.cj.clear()
 
+        if noteResponseTime:
+            kb.responseTimes.append(time.time() - start)
+
         if content or response:
             return page, headers
         elif getSeqMatcher: